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BASH_BUILTINS(1) BASH_BUILTINS(1)
NNAAMMEE
bash, :, ., [, alias, bg, bind, break, builtin, cd, command, compgen,
complete, continue, declare, dirs, disown, echo, enable, eval, exec,
exit, export, fc, fg, getopts, hash, help, history, jobs, kill, let,
local, logout, popd, printf, pushd, pwd, read, readonly, return, set,
shift, shopt, source, suspend, test, times, trap, type, typeset,
ulimit, umask, unalias, unset, wait - bash built-in commands, see
bbaasshh(1)
BBAASSHH BBUUIILLTTIINN CCOOMMMMAANNDDSS
Unless otherwise noted, each builtin command documented in this section
as accepting options preceded by -- accepts ---- to signify the end of the
options. For example, the ::, ttrruuee, ffaallssee, and tteesstt builtins do not
accept options.
:: [_a_r_g_u_m_e_n_t_s]
No effect; the command does nothing beyond expanding _a_r_g_u_m_e_n_t_s
and performing any specified redirections. A zero exit code is
returned.
.. _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s]
ssoouurrccee _f_i_l_e_n_a_m_e [_a_r_g_u_m_e_n_t_s]
Read and execute commands from _f_i_l_e_n_a_m_e in the current shell
environment and return the exit status of the last command exe-
cuted from _f_i_l_e_n_a_m_e. If _f_i_l_e_n_a_m_e does not contain a slash, file
names in PPAATTHH are used to find the directory containing _f_i_l_e_-
_n_a_m_e. The file searched for in PPAATTHH need not be executable.
When bbaasshh is not in _p_o_s_i_x _m_o_d_e, the current directory is
searched if no file is found in PPAATTHH. If the ssoouurrcceeppaatthh option
to the sshhoopptt builtin command is turned off, the PPAATTHH is not
searched. If any _a_r_g_u_m_e_n_t_s are supplied, they become the posi-
tional parameters when _f_i_l_e_n_a_m_e is executed. Otherwise the
positional parameters are unchanged. The return status is the
status of the last command exited within the script (0 if no
commands are executed), and false if _f_i_l_e_n_a_m_e is not found or
cannot be read.
aalliiaass [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
AAlliiaass with no arguments or with the --pp option prints the list of
aliases in the form aalliiaass _n_a_m_e=_v_a_l_u_e on standard output. When
arguments are supplied, an alias is defined for each _n_a_m_e whose
_v_a_l_u_e is given. A trailing space in _v_a_l_u_e causes the next word
to be checked for alias substitution when the alias is expanded.
For each _n_a_m_e in the argument list for which no _v_a_l_u_e is sup-
plied, the name and value of the alias is printed. AAlliiaass
returns true unless a _n_a_m_e is given for which no alias has been
defined.
bbgg [_j_o_b_s_p_e_c ...]
Resume each suspended job _j_o_b_s_p_e_c in the background, as if it
had been started with &&. If _j_o_b_s_p_e_c is not present, the shell's
notion of the _c_u_r_r_e_n_t _j_o_b is used. bbgg _j_o_b_s_p_e_c returns 0 unless
run when job control is disabled or, when run with job control
enabled, any specified _j_o_b_s_p_e_c was not found or was started
without job control.
bbiinndd [--mm _k_e_y_m_a_p] [--llppssvvPPSSVV]
bbiinndd [--mm _k_e_y_m_a_p] [--qq _f_u_n_c_t_i_o_n] [--uu _f_u_n_c_t_i_o_n] [--rr _k_e_y_s_e_q]
bbiinndd [--mm _k_e_y_m_a_p] --ff _f_i_l_e_n_a_m_e
bbiinndd [--mm _k_e_y_m_a_p] --xx _k_e_y_s_e_q:_s_h_e_l_l_-_c_o_m_m_a_n_d
bbiinndd [--mm _k_e_y_m_a_p] _k_e_y_s_e_q:_f_u_n_c_t_i_o_n_-_n_a_m_e
bbiinndd _r_e_a_d_l_i_n_e_-_c_o_m_m_a_n_d
Display current rreeaaddlliinnee key and function bindings, bind a key
sequence to a rreeaaddlliinnee function or macro, or set a rreeaaddlliinnee
variable. Each non-option argument is a command as it would
appear in _._i_n_p_u_t_r_c, but each binding or command must be passed
as a separate argument; e.g., '"\C-x\C-r": re-read-init-file'.
Options, if supplied, have the following meanings:
--mm _k_e_y_m_a_p
Use _k_e_y_m_a_p as the keymap to be affected by the subsequent
bindings. Acceptable _k_e_y_m_a_p names are _e_m_a_c_s_, _e_m_a_c_s_-_s_t_a_n_-
_d_a_r_d_, _e_m_a_c_s_-_m_e_t_a_, _e_m_a_c_s_-_c_t_l_x_, _v_i_, _v_i_-_m_o_v_e_, _v_i_-_c_o_m_m_a_n_d,
and _v_i_-_i_n_s_e_r_t. _v_i is equivalent to _v_i_-_c_o_m_m_a_n_d; _e_m_a_c_s is
equivalent to _e_m_a_c_s_-_s_t_a_n_d_a_r_d.
--ll List the names of all rreeaaddlliinnee functions.
--pp Display rreeaaddlliinnee function names and bindings in such a
way that they can be re-read.
--PP List current rreeaaddlliinnee function names and bindings.
--vv Display rreeaaddlliinnee variable names and values in such a way
that they can be re-read.
--VV List current rreeaaddlliinnee variable names and values.
--ss Display rreeaaddlliinnee key sequences bound to macros and the
strings they output in such a way that they can be re-
read.
--SS Display rreeaaddlliinnee key sequences bound to macros and the
strings they output.
--ff _f_i_l_e_n_a_m_e
Read key bindings from _f_i_l_e_n_a_m_e.
--qq _f_u_n_c_t_i_o_n
Query about which keys invoke the named _f_u_n_c_t_i_o_n.
--uu _f_u_n_c_t_i_o_n
Unbind all keys bound to the named _f_u_n_c_t_i_o_n.
--rr _k_e_y_s_e_q
Remove any current binding for _k_e_y_s_e_q.
--xx _k_e_y_s_e_q::_s_h_e_l_l_-_c_o_m_m_a_n_d
Cause _s_h_e_l_l_-_c_o_m_m_a_n_d to be executed whenever _k_e_y_s_e_q is
entered.
The return value is 0 unless an unrecognized option is given or
an error occurred.
bbrreeaakk [_n]
Exit from within a ffoorr, wwhhiillee, uunnttiill, or sseelleecctt loop. If _n is
specified, break _n levels. _n must be >= 1. If _n is greater
than the number of enclosing loops, all enclosing loops are
exited. The return value is 0 unless the shell is not executing
a loop when bbrreeaakk is executed.
bbuuiillttiinn _s_h_e_l_l_-_b_u_i_l_t_i_n [_a_r_g_u_m_e_n_t_s]
Execute the specified shell builtin, passing it _a_r_g_u_m_e_n_t_s, and
return its exit status. This is useful when defining a function
whose name is the same as a shell builtin, retaining the func-
tionality of the builtin within the function. The ccdd builtin is
commonly redefined this way. The return status is false if
_s_h_e_l_l_-_b_u_i_l_t_i_n is not a shell builtin command.
ccdd [--LL||--PP] [_d_i_r]
Change the current directory to _d_i_r. The variable HHOOMMEE is the
default _d_i_r. The variable CCDDPPAATTHH defines the search path for
the directory containing _d_i_r. Alternative directory names in
CCDDPPAATTHH are separated by a colon (:). A null directory name in
CCDDPPAATTHH is the same as the current directory, i.e., ``..''. If
_d_i_r begins with a slash (/), then CCDDPPAATTHH is not used. The --PP
option says to use the physical directory structure instead of
following symbolic links (see also the --PP option to the sseett
builtin command); the --LL option forces symbolic links to be fol-
lowed. An argument of -- is equivalent to $$OOLLDDPPWWDD. If a non-
empty directory name from CCDDPPAATTHH is used, or if -- is the first
argument, and the directory change is successful, the absolute
pathname of the new working directory is written to the standard
output. The return value is true if the directory was success-
fully changed; false otherwise.
ccaalllleerr [_e_x_p_r]
Returns the context of any active subroutine call (a shell func-
tion or a script executed with the .. or ssoouurrccee builtins. With-
out _e_x_p_r, ccaalllleerr displays the line number and source filename of
the current subroutine call. If a non-negative integer is sup-
plied as _e_x_p_r, ccaalllleerr displays the line number, subroutine name,
and source file corresponding to that position in the current
execution call stack. This extra information may be used, for
example, to print a stack trace. The current frame is frame 0.
The return value is 0 unless the shell is not executing a sub-
routine call or _e_x_p_r does not correspond to a valid position in
the call stack.
ccoommmmaanndd [--ppVVvv] _c_o_m_m_a_n_d [_a_r_g ...]
Run _c_o_m_m_a_n_d with _a_r_g_s suppressing the normal shell function
lookup. Only builtin commands or commands found in the PPAATTHH are
executed. If the --pp option is given, the search for _c_o_m_m_a_n_d is
performed using a default value for PPAATTHH that is guaranteed to
find all of the standard utilities. If either the --VV or --vv
option is supplied, a description of _c_o_m_m_a_n_d is printed. The --vv
option causes a single word indicating the command or file name
used to invoke _c_o_m_m_a_n_d to be displayed; the --VV option produces a
more verbose description. If the --VV or --vv option is supplied,
the exit status is 0 if _c_o_m_m_a_n_d was found, and 1 if not. If
neither option is supplied and an error occurred or _c_o_m_m_a_n_d can-
not be found, the exit status is 127. Otherwise, the exit sta-
tus of the ccoommmmaanndd builtin is the exit status of _c_o_m_m_a_n_d.
ccoommppggeenn [_o_p_t_i_o_n] [_w_o_r_d]
Generate possible completion matches for _w_o_r_d according to the
_o_p_t_i_o_ns, which may be any option accepted by the ccoommpplleettee
builtin with the exception of --pp and --rr, and write the matches
to the standard output. When using the --FF or --CC options, the
various shell variables set by the programmable completion
facilities, while available, will not have useful values.
The matches will be generated in the same way as if the pro-
grammable completion code had generated them directly from a
completion specification with the same flags. If _w_o_r_d is speci-
fied, only those completions matching _w_o_r_d will be displayed.
The return value is true unless an invalid option is supplied,
or no matches were generated.
ccoommpplleettee [--aabbccddeeffggjjkkssuuvv] [--oo _c_o_m_p_-_o_p_t_i_o_n] [--AA _a_c_t_i_o_n] [--GG _g_l_o_b_p_a_t] [--WW
_w_o_r_d_l_i_s_t] [--PP _p_r_e_f_i_x] [--SS _s_u_f_f_i_x]
[--XX _f_i_l_t_e_r_p_a_t] [--FF _f_u_n_c_t_i_o_n] [--CC _c_o_m_m_a_n_d] _n_a_m_e [_n_a_m_e _._._.]
ccoommpplleettee --pprr [_n_a_m_e ...]
Specify how arguments to each _n_a_m_e should be completed. If the
--pp option is supplied, or if no options are supplied, existing
completion specifications are printed in a way that allows them
to be reused as input. The --rr option removes a completion spec-
ification for each _n_a_m_e, or, if no _n_a_m_es are supplied, all com-
pletion specifications.
The process of applying these completion specifications when
word completion is attempted is described above under PPrroo--
ggrraammmmaabbllee CCoommpplleettiioonn.
Other options, if specified, have the following meanings. The
arguments to the --GG, --WW, and --XX options (and, if necessary, the
--PP and --SS options) should be quoted to protect them from expan-
sion before the ccoommpplleettee builtin is invoked.
--oo _c_o_m_p_-_o_p_t_i_o_n
The _c_o_m_p_-_o_p_t_i_o_n controls several aspects of the comp-
spec's behavior beyond the simple generation of comple-
tions. _c_o_m_p_-_o_p_t_i_o_n may be one of:
bbaasshhddeeffaauulltt
Perform the rest of the default bbaasshh completions
if the compspec generates no matches.
ddeeffaauulltt Use readline's default filename completion if
the compspec generates no matches.
ddiirrnnaammeess
Perform directory name completion if the comp-
spec generates no matches.
ffiilleennaammeess
Tell readline that the compspec generates file-
names, so it can perform any filename-specific
processing (like adding a slash to directory
names or suppressing trailing spaces). Intended
to be used with shell functions.
nnoossppaaccee Tell readline not to append a space (the
default) to words completed at the end of the
line.
pplluussddiirrss
After any matches defined by the compspec are
generated, directory name completion is
attempted and any matches are added to the
results of the other actions.
--AA _a_c_t_i_o_n
The _a_c_t_i_o_n may be one of the following to generate a
list of possible completions:
aalliiaass Alias names. May also be specified as --aa.
aarrrraayyvvaarr
Array variable names.
bbiinnddiinngg RReeaaddlliinnee key binding names.
bbuuiillttiinn Names of shell builtin commands. May also be
specified as --bb.
ccoommmmaanndd Command names. May also be specified as --cc.
ddiirreeccttoorryy
Directory names. May also be specified as --dd.
ddiissaabblleedd
Names of disabled shell builtins.
eennaabblleedd Names of enabled shell builtins.
eexxppoorrtt Names of exported shell variables. May also be
specified as --ee.
ffiillee File names. May also be specified as --ff.
ffuunnccttiioonn
Names of shell functions.
ggrroouupp Group names. May also be specified as --gg.
hheellppttooppiicc
Help topics as accepted by the hheellpp builtin.
hhoossttnnaammee
Hostnames, as taken from the file specified by
the HHOOSSTTFFIILLEE shell variable.
jjoobb Job names, if job control is active. May also
be specified as --jj.
kkeeyywwoorrdd Shell reserved words. May also be specified as
--kk.
rruunnnniinngg Names of running jobs, if job control is active.
sseerrvviiccee Service names. May also be specified as --ss.
sseettoopptt Valid arguments for the --oo option to the sseett
builtin.
sshhoopptt Shell option names as accepted by the sshhoopptt
builtin.
ssiiggnnaall Signal names.
ssttooppppeedd Names of stopped jobs, if job control is active.
uusseerr User names. May also be specified as --uu.
vvaarriiaabbllee
Names of all shell variables. May also be spec-
ified as --vv.
--GG _g_l_o_b_p_a_t
The filename expansion pattern _g_l_o_b_p_a_t is expanded to
generate the possible completions.
--WW _w_o_r_d_l_i_s_t
The _w_o_r_d_l_i_s_t is split using the characters in the IIFFSS
special variable as delimiters, and each resultant word
is expanded. The possible completions are the members
of the resultant list which match the word being com-
pleted.
--CC _c_o_m_m_a_n_d
_c_o_m_m_a_n_d is executed in a subshell environment, and its
output is used as the possible completions.
--FF _f_u_n_c_t_i_o_n
The shell function _f_u_n_c_t_i_o_n is executed in the current
shell environment. When it finishes, the possible com-
pletions are retrieved from the value of the CCOOMMPPRREEPPLLYY
array variable.
--XX _f_i_l_t_e_r_p_a_t
_f_i_l_t_e_r_p_a_t is a pattern as used for filename expansion.
It is applied to the list of possible completions gener-
ated by the preceding options and arguments, and each
completion matching _f_i_l_t_e_r_p_a_t is removed from the list.
A leading !! in _f_i_l_t_e_r_p_a_t negates the pattern; in this
case, any completion not matching _f_i_l_t_e_r_p_a_t is removed.
--PP _p_r_e_f_i_x
_p_r_e_f_i_x is added at the beginning of each possible com-
pletion after all other options have been applied.
--SS _s_u_f_f_i_x
_s_u_f_f_i_x is appended to each possible completion after all
other options have been applied.
The return value is true unless an invalid option is supplied,
an option other than --pp or --rr is supplied without a _n_a_m_e argu-
ment, an attempt is made to remove a completion specification
for a _n_a_m_e for which no specification exists, or an error occurs
adding a completion specification.
ccoonnttiinnuuee [_n]
Resume the next iteration of the enclosing ffoorr, wwhhiillee, uunnttiill, or
sseelleecctt loop. If _n is specified, resume at the _nth enclosing
loop. _n must be >= 1. If _n is greater than the number of
enclosing loops, the last enclosing loop (the ``top-level''
loop) is resumed. The return value is 0 unless the shell is not
executing a loop when ccoonnttiinnuuee is executed.
ddeeccllaarree [--aaffFFiirrttxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
ttyyppeesseett [--aaffFFiirrttxx] [--pp] [_n_a_m_e[=_v_a_l_u_e] ...]
Declare variables and/or give them attributes. If no _n_a_m_es are
given then display the values of variables. The --pp option will
display the attributes and values of each _n_a_m_e. When --pp is
used, additional options are ignored. The --FF option inhibits
the display of function definitions; only the function name and
attributes are printed. If the eexxttddeebbuugg shell option is enabled
using sshhoopptt, the source file name and line number where the
function is defined are displayed as well. The --FF option
implies --ff. The following options can be used to restrict out-
put to variables with the specified attribute or to give vari-
ables attributes:
--aa Each _n_a_m_e is an array variable (see AArrrraayyss above).
--ff Use function names only.
--ii The variable is treated as an integer; arithmetic evalua-
tion (see AARRIITTHHMMEETTIICC EEVVAALLUUAATTIIOONN )) is performed when the
variable is assigned a value.
--rr Make _n_a_m_es readonly. These names cannot then be assigned
values by subsequent assignment statements or unset.
--tt Give each _n_a_m_e the _t_r_a_c_e attribute. Traced functions
inherit the DDEEBBUUGG and RREETTUURRNN traps from the calling
shell. The trace attribute has no special meaning for
variables.
--xx Mark _n_a_m_es for export to subsequent commands via the
environment.
Using `+' instead of `-' turns off the attribute instead, with
the exception that ++aa may not be used to destroy an array vari-
able. When used in a function, makes each _n_a_m_e local, as with
the llooccaall command. If a variable name is followed by =_v_a_l_u_e,
the value of the variable is set to _v_a_l_u_e. The return value is
0 unless an invalid option is encountered, an attempt is made to
define a function using ``-f foo=bar'', an attempt is made to
assign a value to a readonly variable, an attempt is made to
assign a value to an array variable without using the compound
assignment syntax (see AArrrraayyss above), one of the _n_a_m_e_s is not a
valid shell variable name, an attempt is made to turn off read-
only status for a readonly variable, an attempt is made to turn
off array status for an array variable, or an attempt is made to
display a non-existent function with --ff.
ddiirrss [[--ccllppvv]] [[++_n]] [[--_n]]
Without options, displays the list of currently remembered
directories. The default display is on a single line with
directory names separated by spaces. Directories are added to
the list with the ppuusshhdd command; the ppooppdd command removes
entries from the list.
++_n Displays the _nth entry counting from the left of the list
shown by ddiirrss when invoked without options, starting with
zero.
--_n Displays the _nth entry counting from the right of the
list shown by ddiirrss when invoked without options, starting
with zero.
--cc Clears the directory stack by deleting all of the
entries.
--ll Produces a longer listing; the default listing format
uses a tilde to denote the home directory.
--pp Print the directory stack with one entry per line.
--vv Print the directory stack with one entry per line, pre-
fixing each entry with its index in the stack.
The return value is 0 unless an invalid option is supplied or _n
indexes beyond the end of the directory stack.
ddiissoowwnn [--aarr] [--hh] [_j_o_b_s_p_e_c ...]
Without options, each _j_o_b_s_p_e_c is removed from the table of
active jobs. If the --hh option is given, each _j_o_b_s_p_e_c is not
removed from the table, but is marked so that SSIIGGHHUUPP is not sent
to the job if the shell receives a SSIIGGHHUUPP. If no _j_o_b_s_p_e_c is
present, and neither the --aa nor the --rr option is supplied, the
_c_u_r_r_e_n_t _j_o_b is used. If no _j_o_b_s_p_e_c is supplied, the --aa option
means to remove or mark all jobs; the --rr option without a _j_o_b_-
_s_p_e_c argument restricts operation to running jobs. The return
value is 0 unless a _j_o_b_s_p_e_c does not specify a valid job.
eecchhoo [--nneeEE] [_a_r_g ...]
Output the _a_r_gs, separated by spaces, followed by a newline.
The return status is always 0. If --nn is specified, the trailing
newline is suppressed. If the --ee option is given, interpreta-
tion of the following backslash-escaped characters is enabled.
The --EE option disables the interpretation of these escape char-
acters, even on systems where they are interpreted by default.
The xxppgg__eecchhoo shell option may be used to dynamically determine
whether or not eecchhoo expands these escape characters by default.
eecchhoo does not interpret ---- to mean the end of options. eecchhoo
interprets the following escape sequences:
\\aa alert (bell)
\\bb backspace
\\cc suppress trailing newline
\\ee an escape character
\\ff form feed
\\nn new line
\\rr carriage return
\\tt horizontal tab
\\vv vertical tab
\\\\ backslash
\\00_n_n_n the eight-bit character whose value is the octal value
_n_n_n (zero to three octal digits)
\\xx_H_H the eight-bit character whose value is the hexadecimal
value _H_H (one or two hex digits)
eennaabbllee [--aaddnnppss] [--ff _f_i_l_e_n_a_m_e] [_n_a_m_e ...]
Enable and disable builtin shell commands. Disabling a builtin
allows a disk command which has the same name as a shell builtin
to be executed without specifying a full pathname, even though
the shell normally searches for builtins before disk commands.
If --nn is used, each _n_a_m_e is disabled; otherwise, _n_a_m_e_s are
enabled. For example, to use the tteesstt binary found via the PPAATTHH
instead of the shell builtin version, run ``enable -n test''.
The --ff option means to load the new builtin command _n_a_m_e from
shared object _f_i_l_e_n_a_m_e, on systems that support dynamic loading.
The --dd option will delete a builtin previously loaded with --ff.
If no _n_a_m_e arguments are given, or if the --pp option is supplied,
a list of shell builtins is printed. With no other option argu-
ments, the list consists of all enabled shell builtins. If --nn
is supplied, only disabled builtins are printed. If --aa is sup-
plied, the list printed includes all builtins, with an indica-
tion of whether or not each is enabled. If --ss is supplied, the
output is restricted to the POSIX _s_p_e_c_i_a_l builtins. The return
value is 0 unless a _n_a_m_e is not a shell builtin or there is an
error loading a new builtin from a shared object.
eevvaall [_a_r_g ...]
The _a_r_gs are read and concatenated together into a single com-
mand. This command is then read and executed by the shell, and
its exit status is returned as the value of eevvaall. If there are
no _a_r_g_s, or only null arguments, eevvaall returns 0.
eexxeecc [--ccll] [--aa _n_a_m_e] [_c_o_m_m_a_n_d [_a_r_g_u_m_e_n_t_s]]
If _c_o_m_m_a_n_d is specified, it replaces the shell. No new process
is created. The _a_r_g_u_m_e_n_t_s become the arguments to _c_o_m_m_a_n_d. If
the --ll option is supplied, the shell places a dash at the begin-
ning of the zeroth arg passed to _c_o_m_m_a_n_d. This is what _l_o_g_i_n(1)
does. The --cc option causes _c_o_m_m_a_n_d to be executed with an empty
environment. If --aa is supplied, the shell passes _n_a_m_e as the
zeroth argument to the executed command. If _c_o_m_m_a_n_d cannot be
executed for some reason, a non-interactive shell exits, unless
the shell option eexxeeccffaaiill is enabled, in which case it returns
failure. An interactive shell returns failure if the file can-
not be executed. If _c_o_m_m_a_n_d is not specified, any redirections
take effect in the current shell, and the return status is 0.
If there is a redirection error, the return status is 1.
eexxiitt [_n]
Cause the shell to exit with a status of _n. If _n is omitted,
the exit status is that of the last command executed. A trap on
EEXXIITT is executed before the shell terminates.
eexxppoorrtt [--ffnn] [_n_a_m_e[=_w_o_r_d]] ...
eexxppoorrtt --pp
The supplied _n_a_m_e_s are marked for automatic export to the envi-
ronment of subsequently executed commands. If the --ff option is
given, the _n_a_m_e_s refer to functions. If no _n_a_m_e_s are given, or
if the --pp option is supplied, a list of all names that are
exported in this shell is printed. The --nn option causes the
export property to be removed from each _n_a_m_e. If a variable
name is followed by =_w_o_r_d, the value of the variable is set to
_w_o_r_d. eexxppoorrtt returns an exit status of 0 unless an invalid
option is encountered, one of the _n_a_m_e_s is not a valid shell
variable name, or --ff is supplied with a _n_a_m_e that is not a func-
tion.
ffcc [--ee _e_n_a_m_e] [--nnllrr] [_f_i_r_s_t] [_l_a_s_t]
ffcc --ss [_p_a_t=_r_e_p] [_c_m_d]
Fix Command. In the first form, a range of commands from _f_i_r_s_t
to _l_a_s_t is selected from the history list. _F_i_r_s_t and _l_a_s_t may
be specified as a string (to locate the last command beginning
with that string) or as a number (an index into the history
list, where a negative number is used as an offset from the cur-
rent command number). If _l_a_s_t is not specified it is set to the
current command for listing (so that ``fc -l -10'' prints the
last 10 commands) and to _f_i_r_s_t otherwise. If _f_i_r_s_t is not spec-
ified it is set to the previous command for editing and -16 for
listing.
The --nn option suppresses the command numbers when listing. The
--rr option reverses the order of the commands. If the --ll option
is given, the commands are listed on standard output. Other-
wise, the editor given by _e_n_a_m_e is invoked on a file containing
those commands. If _e_n_a_m_e is not given, the value of the FFCCEEDDIITT
variable is used, and the value of EEDDIITTOORR if FFCCEEDDIITT is not set.
If neither variable is set, is used. When editing is complete,
the edited commands are echoed and executed.
In the second form, _c_o_m_m_a_n_d is re-executed after each instance
of _p_a_t is replaced by _r_e_p. A useful alias to use with this is
``r="fc -s"'', so that typing ``r cc'' runs the last command
beginning with ``cc'' and typing ``r'' re-executes the last com-
mand.
If the first form is used, the return value is 0 unless an
invalid option is encountered or _f_i_r_s_t or _l_a_s_t specify history
lines out of range. If the --ee option is supplied, the return
value is the value of the last command executed or failure if an
error occurs with the temporary file of commands. If the second
form is used, the return status is that of the command re-exe-
cuted, unless _c_m_d does not specify a valid history line, in
which case ffcc returns failure.
ffgg [_j_o_b_s_p_e_c]
Resume _j_o_b_s_p_e_c in the foreground, and make it the current job.
If _j_o_b_s_p_e_c is not present, the shell's notion of the _c_u_r_r_e_n_t _j_o_b
is used. The return value is that of the command placed into
the foreground, or failure if run when job control is disabled
or, when run with job control enabled, if _j_o_b_s_p_e_c does not spec-
ify a valid job or _j_o_b_s_p_e_c specifies a job that was started
without job control.
ggeettooppttss _o_p_t_s_t_r_i_n_g _n_a_m_e [_a_r_g_s]
ggeettooppttss is used by shell procedures to parse positional parame-
ters. _o_p_t_s_t_r_i_n_g contains the option characters to be recog-
nized; if a character is followed by a colon, the option is
expected to have an argument, which should be separated from it
by white space. The colon and question mark characters may not
be used as option characters. Each time it is invoked, ggeettooppttss
places the next option in the shell variable _n_a_m_e, initializing
_n_a_m_e if it does not exist, and the index of the next argument to
be processed into the variable OOPPTTIINNDD. OOPPTTIINNDD is initialized to
1 each time the shell or a shell script is invoked. When an
option requires an argument, ggeettooppttss places that argument into
the variable OOPPTTAARRGG. The shell does not reset OOPPTTIINNDD automati-
cally; it must be manually reset between multiple calls to
ggeettooppttss within the same shell invocation if a new set of parame-
ters is to be used.
When the end of options is encountered, ggeettooppttss exits with a
return value greater than zero. OOPPTTIINNDD is set to the index of
the first non-option argument, and nnaammee is set to ?.
ggeettooppttss normally parses the positional parameters, but if more
arguments are given in _a_r_g_s, ggeettooppttss parses those instead.
ggeettooppttss can report errors in two ways. If the first character
of _o_p_t_s_t_r_i_n_g is a colon, _s_i_l_e_n_t error reporting is used. In
normal operation diagnostic messages are printed when invalid
options or missing option arguments are encountered. If the
variable OOPPTTEERRRR is set to 0, no error messages will be dis-
played, even if the first character of _o_p_t_s_t_r_i_n_g is not a colon.
If an invalid option is seen, ggeettooppttss places ? into _n_a_m_e and, if
not silent, prints an error message and unsets OOPPTTAARRGG. If
ggeettooppttss is silent, the option character found is placed in
OOPPTTAARRGG and no diagnostic message is printed.
If a required argument is not found, and ggeettooppttss is not silent,
a question mark (??) is placed in _n_a_m_e, OOPPTTAARRGG is unset, and a
diagnostic message is printed. If ggeettooppttss is silent, then a
colon (::) is placed in _n_a_m_e and OOPPTTAARRGG is set to the option
character found.
ggeettooppttss returns true if an option, specified or unspecified, is
found. It returns false if the end of options is encountered or
an error occurs.
hhaasshh [--llrr] [--pp _f_i_l_e_n_a_m_e] [--ddtt] [_n_a_m_e]
For each _n_a_m_e, the full file name of the command is determined
by searching the directories in $$PPAATTHH and remembered. If the --pp
option is supplied, no path search is performed, and _f_i_l_e_n_a_m_e is
used as the full file name of the command. The --rr option causes
the shell to forget all remembered locations. The --dd option
causes the shell to forget the remembered location of each _n_a_m_e.
If the --tt option is supplied, the full pathname to which each
_n_a_m_e corresponds is printed. If multiple _n_a_m_e arguments are
supplied with --tt, the _n_a_m_e is printed before the hashed full
pathname. The --ll option causes output to be displayed in a for-
mat that may be reused as input. If no arguments are given, or
if only --ll is supplied, information about remembered commands is
printed. The return status is true unless a _n_a_m_e is not found
or an invalid option is supplied.
hheellpp [--ss] [_p_a_t_t_e_r_n]
Display helpful information about builtin commands. If _p_a_t_t_e_r_n
is specified, hheellpp gives detailed help on all commands matching
_p_a_t_t_e_r_n; otherwise help for all the builtins and shell control
structures is printed. The --ss option restricts the information
displayed to a short usage synopsis. The return status is 0
unless no command matches _p_a_t_t_e_r_n.
hhiissttoorryy [[_n]]
hhiissttoorryy --cc
hhiissttoorryy --dd _o_f_f_s_e_t
hhiissttoorryy --aannrrww [_f_i_l_e_n_a_m_e]
hhiissttoorryy --pp _a_r_g [_a_r_g _._._.]
hhiissttoorryy --ss _a_r_g [_a_r_g _._._.]
With no options, display the command history list with line num-
bers. Lines listed with a ** have been modified. An argument of
_n lists only the last _n lines. If the shell variable HHIISSTTTTIIMMEE--
FFOORRMMAATT is set and not null, it is used as a format string for
_s_t_r_f_t_i_m_e(3) to display the time stamp associated with each dis-
played history entry. No intervening blank is printed between
the formatted time stamp and the history line. If _f_i_l_e_n_a_m_e is
supplied, it is used as the name of the history file; if not,
the value of HHIISSTTFFIILLEE is used. Options, if supplied, have the
following meanings:
--cc Clear the history list by deleting all the entries.
--dd _o_f_f_s_e_t
Delete the history entry at position _o_f_f_s_e_t.
--aa Append the ``new'' history lines (history lines entered
since the beginning of the current bbaasshh session) to the
history file.
--nn Read the history lines not already read from the history
file into the current history list. These are lines
appended to the history file since the beginning of the
current bbaasshh session.
--rr Read the contents of the history file and use them as the
current history.
--ww Write the current history to the history file, overwrit-
ing the history file's contents.
--pp Perform history substitution on the following _a_r_g_s and
display the result on the standard output. Does not
store the results in the history list. Each _a_r_g must be
quoted to disable normal history expansion.
--ss Store the _a_r_g_s in the history list as a single entry.
The last command in the history list is removed before
the _a_r_g_s are added.
If the HHIISSTTTTIIMMEEFFOORRMMAATT is set, the time stamp information associ-
ated with each history entry is written to the history file.
The return value is 0 unless an invalid option is encountered,
an error occurs while reading or writing the history file, an
invalid _o_f_f_s_e_t is supplied as an argument to --dd, or the history
expansion supplied as an argument to --pp fails.
jjoobbss [--llnnpprrss] [ _j_o_b_s_p_e_c ... ]
jjoobbss --xx _c_o_m_m_a_n_d [ _a_r_g_s ... ]
The first form lists the active jobs. The options have the fol-
lowing meanings:
--ll List process IDs in addition to the normal information.
--pp List only the process ID of the job's process group
leader.
--nn Display information only about jobs that have changed
status since the user was last notified of their status.
--rr Restrict output to running jobs.
--ss Restrict output to stopped jobs.
If _j_o_b_s_p_e_c is given, output is restricted to information about
that job. The return status is 0 unless an invalid option is
encountered or an invalid _j_o_b_s_p_e_c is supplied.
If the --xx option is supplied, jjoobbss replaces any _j_o_b_s_p_e_c found in
_c_o_m_m_a_n_d or _a_r_g_s with the corresponding process group ID, and
executes _c_o_m_m_a_n_d passing it _a_r_g_s, returning its exit status.
kkiillll [--ss _s_i_g_s_p_e_c | --nn _s_i_g_n_u_m | --_s_i_g_s_p_e_c] [_p_i_d | _j_o_b_s_p_e_c] ...
kkiillll --ll [_s_i_g_s_p_e_c | _e_x_i_t___s_t_a_t_u_s]
Send the signal named by _s_i_g_s_p_e_c or _s_i_g_n_u_m to the processes
named by _p_i_d or _j_o_b_s_p_e_c. _s_i_g_s_p_e_c is either a case-insensitive
signal name such as SSIIGGKKIILLLL (with or without the SSIIGG prefix) or
a signal number; _s_i_g_n_u_m is a signal number. If _s_i_g_s_p_e_c is not
present, then SSIIGGTTEERRMM is assumed. An argument of --ll lists the
signal names. If any arguments are supplied when --ll is given,
the names of the signals corresponding to the arguments are
listed, and the return status is 0. The _e_x_i_t___s_t_a_t_u_s argument to
--ll is a number specifying either a signal number or the exit
status of a process terminated by a signal. kkiillll returns true
if at least one signal was successfully sent, or false if an
error occurs or an invalid option is encountered.
lleett _a_r_g [_a_r_g ...]
Each _a_r_g is an arithmetic expression to be evaluated (see AARRIITTHH--
MMEETTIICC EEVVAALLUUAATTIIOONN). If the last _a_r_g evaluates to 0, lleett returns
1; 0 is returned otherwise.
llooccaall [_o_p_t_i_o_n] [_n_a_m_e[=_v_a_l_u_e] ...]
For each argument, a local variable named _n_a_m_e is created, and
assigned _v_a_l_u_e. The _o_p_t_i_o_n can be any of the options accepted
by ddeeccllaarree. When llooccaall is used within a function, it causes the
variable _n_a_m_e to have a visible scope restricted to that func-
tion and its children. With no operands, llooccaall writes a list of
local variables to the standard output. It is an error to use
llooccaall when not within a function. The return status is 0 unless
llooccaall is used outside a function, an invalid _n_a_m_e is supplied,
or _n_a_m_e is a readonly variable.
llooggoouutt Exit a login shell.
ppooppdd [-nn] [+_n] [-_n]
Removes entries from the directory stack. With no arguments,
removes the top directory from the stack, and performs a ccdd to
the new top directory. Arguments, if supplied, have the follow-
ing meanings:
++_n Removes the _nth entry counting from the left of the list
shown by ddiirrss, starting with zero. For example: ``popd
+0'' removes the first directory, ``popd +1'' the second.
--_n Removes the _nth entry counting from the right of the list
shown by ddiirrss, starting with zero. For example: ``popd
-0'' removes the last directory, ``popd -1'' the next to
last.
--nn Suppresses the normal change of directory when removing
directories from the stack, so that only the stack is
manipulated.
If the ppooppdd command is successful, a ddiirrss is performed as well,
and the return status is 0. ppooppdd returns false if an invalid
option is encountered, the directory stack is empty, a non-exis-
tent directory stack entry is specified, or the directory change
fails.
pprriinnttff [--vv _v_a_r] _f_o_r_m_a_t [_a_r_g_u_m_e_n_t_s]
Write the formatted _a_r_g_u_m_e_n_t_s to the standard output under the
control of the _f_o_r_m_a_t. The _f_o_r_m_a_t is a character string which
contains three types of objects: plain characters, which are
simply copied to standard output, character escape sequences,
which are converted and copied to the standard output, and for-
mat specifications, each of which causes printing of the next
successive _a_r_g_u_m_e_n_t. In addition to the standard _p_r_i_n_t_f(1) for-
mats, %%bb causes pprriinnttff to expand backslash escape sequences in
the corresponding _a_r_g_u_m_e_n_t (except that \\cc terminates output,
backslashes in \\'', \\"", and \\?? are not removed, and octal escapes
beginning with \\00 may contain up to four digits), and %%qq causes
pprriinnttff to output the corresponding _a_r_g_u_m_e_n_t in a format that can
be reused as shell input.
The --vv option causes the output to be assigned to the variable
_v_a_r rather than being printed to the standard output.
The _f_o_r_m_a_t is reused as necessary to consume all of the _a_r_g_u_-
_m_e_n_t_s. If the _f_o_r_m_a_t requires more _a_r_g_u_m_e_n_t_s than are supplied,
the extra format specifications behave as if a zero value or
null string, as appropriate, had been supplied. The return
value is zero on success, non-zero on failure.
ppuusshhdd [--nn] [_d_i_r]
ppuusshhdd [--nn] [+_n] [-_n]
Adds a directory to the top of the directory stack, or rotates
the stack, making the new top of the stack the current working
directory. With no arguments, exchanges the top two directories
and returns 0, unless the directory stack is empty. Arguments,
if supplied, have the following meanings:
++_n Rotates the stack so that the _nth directory (counting
from the left of the list shown by ddiirrss, starting with
zero) is at the top.
--_n Rotates the stack so that the _nth directory (counting
from the right of the list shown by ddiirrss, starting with
zero) is at the top.
--nn Suppresses the normal change of directory when adding
directories to the stack, so that only the stack is
manipulated.
_d_i_r Adds _d_i_r to the directory stack at the top, making it the
new current working directory.
If the ppuusshhdd command is successful, a ddiirrss is performed as well.
If the first form is used, ppuusshhdd returns 0 unless the cd to _d_i_r
fails. With the second form, ppuusshhdd returns 0 unless the direc-
tory stack is empty, a non-existent directory stack element is
specified, or the directory change to the specified new current
directory fails.
ppwwdd [--LLPP]
Print the absolute pathname of the current working directory.
The pathname printed contains no symbolic links if the --PP option
is supplied or the --oo pphhyyssiiccaall option to the sseett builtin command
is enabled. If the --LL option is used, the pathname printed may
contain symbolic links. The return status is 0 unless an error
occurs while reading the name of the current directory or an
invalid option is supplied.
rreeaadd [--eerrss] [--uu _f_d] [--tt _t_i_m_e_o_u_t] [--aa _a_n_a_m_e] [--pp _p_r_o_m_p_t] [--nn _n_c_h_a_r_s] [--dd
_d_e_l_i_m] [_n_a_m_e ...]
One line is read from the standard input, or from the file
descriptor _f_d supplied as an argument to the --uu option, and the
first word is assigned to the first _n_a_m_e, the second word to the
second _n_a_m_e, and so on, with leftover words and their interven-
ing separators assigned to the last _n_a_m_e. If there are fewer
words read from the input stream than names, the remaining names
are assigned empty values. The characters in IIFFSS are used to
split the line into words. The backslash character (\\) may be
used to remove any special meaning for the next character read
and for line continuation. Options, if supplied, have the fol-
lowing meanings:
--aa _a_n_a_m_e
The words are assigned to sequential indices of the array
variable _a_n_a_m_e, starting at 0. _a_n_a_m_e is unset before any
new values are assigned. Other _n_a_m_e arguments are
ignored.
--dd _d_e_l_i_m
The first character of _d_e_l_i_m is used to terminate the
input line, rather than newline.
--ee If the standard input is coming from a terminal, rreeaaddlliinnee
(see RREEAADDLLIINNEE above) is used to obtain the line.
--nn _n_c_h_a_r_s
rreeaadd returns after reading _n_c_h_a_r_s characters rather than
waiting for a complete line of input.
--pp _p_r_o_m_p_t
Display _p_r_o_m_p_t on standard error, without a trailing new-
line, before attempting to read any input. The prompt is
displayed only if input is coming from a terminal.
--rr Backslash does not act as an escape character. The back-
slash is considered to be part of the line. In particu-
lar, a backslash-newline pair may not be used as a line
continuation.
--ss Silent mode. If input is coming from a terminal, charac-
ters are not echoed.
--tt _t_i_m_e_o_u_t
Cause rreeaadd to time out and return failure if a complete
line of input is not read within _t_i_m_e_o_u_t seconds. This
option has no effect if rreeaadd is not reading input from
the terminal or a pipe.
--uu _f_d Read input from file descriptor _f_d.
If no _n_a_m_e_s are supplied, the line read is assigned to the vari-
able RREEPPLLYY. The return code is zero, unless end-of-file is
encountered, rreeaadd times out, or an invalid file descriptor is
supplied as the argument to --uu.
rreeaaddoonnllyy [--aappff] [_n_a_m_e[=_w_o_r_d] ...]
The given _n_a_m_e_s are marked readonly; the values of these _n_a_m_e_s
may not be changed by subsequent assignment. If the --ff option
is supplied, the functions corresponding to the _n_a_m_e_s are so
marked. The --aa option restricts the variables to arrays. If no
_n_a_m_e arguments are given, or if the --pp option is supplied, a
list of all readonly names is printed. The --pp option causes
output to be displayed in a format that may be reused as input.
If a variable name is followed by =_w_o_r_d, the value of the vari-
able is set to _w_o_r_d. The return status is 0 unless an invalid
option is encountered, one of the _n_a_m_e_s is not a valid shell
variable name, or --ff is supplied with a _n_a_m_e that is not a func-
tion.
rreettuurrnn [_n]
Causes a function to exit with the return value specified by _n.
If _n is omitted, the return status is that of the last command
executed in the function body. If used outside a function, but
during execution of a script by the .. (ssoouurrccee) command, it
causes the shell to stop executing that script and return either
_n or the exit status of the last command executed within the
script as the exit status of the script. If used outside a
function and not during execution of a script by .., the return
status is false. Any command associated with the RREETTUURRNN trap is
executed before execution resumes after the function or script.
sseett [----aabbeeffhhkkmmnnppttuuvvxxBBCCHHPP] [--oo _o_p_t_i_o_n] [_a_r_g ...]
Without options, the name and value of each shell variable are
displayed in a format that can be reused as input for setting or
resetting the currently-set variables. Read-only variables can-
not be reset. In _p_o_s_i_x _m_o_d_e, only shell variables are listed.
The output is sorted according to the current locale. When
options are specified, they set or unset shell attributes. Any
arguments remaining after the options are processed are treated
as values for the positional parameters and are assigned, in
order, to $$11, $$22, ...... $$_n. Options, if specified, have the fol-
lowing meanings:
--aa Automatically mark variables and functions which are
modified or created for export to the environment of
subsequent commands.
--bb Report the status of terminated background jobs immedi-
ately, rather than before the next primary prompt. This
is effective only when job control is enabled.
--ee Exit immediately if a _s_i_m_p_l_e _c_o_m_m_a_n_d (see SSHHEELLLL GGRRAAMMMMAARR
above) exits with a non-zero status. The shell does not
exit if the command that fails is part of the command
list immediately following a wwhhiillee or uunnttiill keyword,
part of the test in an _i_f statement, part of a &&&& or ||||
list, or if the command's return value is being inverted
via !!. A trap on EERRRR, if set, is executed before the
shell exits.
--ff Disable pathname expansion.
--hh Remember the location of commands as they are looked up
for execution. This is enabled by default.
--kk All arguments in the form of assignment statements are
placed in the environment for a command, not just those
that precede the command name.
--mm Monitor mode. Job control is enabled. This option is
on by default for interactive shells on systems that
support it (see JJOOBB CCOONNTTRROOLL above). Background pro-
cesses run in a separate process group and a line con-
taining their exit status is printed upon their comple-
tion.
--nn Read commands but do not execute them. This may be used
to check a shell script for syntax errors. This is
ignored by interactive shells.
--oo _o_p_t_i_o_n_-_n_a_m_e
The _o_p_t_i_o_n_-_n_a_m_e can be one of the following:
aalllleexxppoorrtt
Same as --aa.
bbrraacceeeexxppaanndd
Same as --BB.
eemmaaccss Use an emacs-style command line editing inter-
face. This is enabled by default when the shell
is interactive, unless the shell is started with
the ----nnooeeddiittiinngg option.
eerrrrttrraaccee
Same as --EE.
ffuunnccttrraaccee
Same as --TT.
eerrrreexxiitt Same as --ee.
hhaasshhaallll Same as --hh.
hhiisstteexxppaanndd
Same as --HH.
hhiissttoorryy Enable command history, as described above under
HHIISSTTOORRYY. This option is on by default in inter-
active shells.
iiggnnoorreeeeooff
The effect is as if the shell command
``IGNOREEOF=10'' had been executed (see SShheellll
VVaarriiaabblleess above).
kkeeyywwoorrdd Same as --kk.
mmoonniittoorr Same as --mm.
nnoocclloobbbbeerr
Same as --CC.
nnooeexxeecc Same as --nn.
nnoogglloobb Same as --ff. nnoolloogg Currently ignored.
nnoottiiffyy Same as --bb.
nnoouunnsseett Same as --uu.
oonneeccmmdd Same as --tt.
pphhyyssiiccaall
Same as --PP.
ppiippeeffaaiill
If set, the return value of a pipeline is the
value of the last (rightmost) command to exit
with a non-zero status, or zero if all commands
in the pipeline exit successfully. This option
is disabled by default.
ppoossiixx Change the behavior of bbaasshh where the default
operation differs from the POSIX standard to
match the standard (_p_o_s_i_x _m_o_d_e).
pprriivviilleeggeedd
Same as --pp.
vveerrbboossee Same as --vv.
vvii Use a vi-style command line editing interface.
xxttrraaccee Same as --xx.
If --oo is supplied with no _o_p_t_i_o_n_-_n_a_m_e, the values of the
current options are printed. If ++oo is supplied with no
_o_p_t_i_o_n_-_n_a_m_e, a series of sseett commands to recreate the
current option settings is displayed on the standard
output.
--pp Turn on _p_r_i_v_i_l_e_g_e_d mode. In this mode, the $$EENNVV and
$$BBAASSHH__EENNVV files are not processed, shell functions are
not inherited from the environment, and the SSHHEELLLLOOPPTTSS
variable, if it appears in the environment, is ignored.
If the shell is started with the effective user (group)
id not equal to the real user (group) id, and the --pp
option is not supplied, these actions are taken and the
effective user id is set to the real user id. If the --pp
option is supplied at startup, the effective user id is
not reset. Turning this option off causes the effective
user and group ids to be set to the real user and group
ids.
--tt Exit after reading and executing one command.
--uu Treat unset variables as an error when performing param-
eter expansion. If expansion is attempted on an unset
variable, the shell prints an error message, and, if not
interactive, exits with a non-zero status.
--vv Print shell input lines as they are read.
--xx After expanding each _s_i_m_p_l_e _c_o_m_m_a_n_d, ffoorr command, ccaassee
command, sseelleecctt command, or arithmetic ffoorr command, dis-
play the expanded value of PPSS44, followed by the command
and its expanded arguments or associated word list.
--BB The shell performs brace expansion (see BBrraaccee EExxppaannssiioonn
above). This is on by default.
--CC If set, bbaasshh does not overwrite an existing file with
the >>, >>&&, and <<>> redirection operators. This may be
overridden when creating output files by using the redi-
rection operator >>|| instead of >>.
--EE If set, any trap on EERRRR is inherited by shell functions,
command substitutions, and commands executed in a sub-
shell environment. The EERRRR trap is normally not inher-
ited in such cases.
--HH Enable !! style history substitution. This option is on
by default when the shell is interactive.
--PP If set, the shell does not follow symbolic links when
executing commands such as ccdd that change the current
working directory. It uses the physical directory
structure instead. By default, bbaasshh follows the logical
chain of directories when performing commands which
change the current directory.
--TT If set, any traps on DDEEBBUUGG and RREETTUURRNN are inherited by
shell functions, command substitutions, and commands
executed in a subshell environment. The DDEEBBUUGG and
RREETTUURRNN traps are normally not inherited in such cases.
---- If no arguments follow this option, then the positional
parameters are unset. Otherwise, the positional parame-
ters are set to the _a_r_gs, even if some of them begin
with a --.
-- Signal the end of options, cause all remaining _a_r_gs to
be assigned to the positional parameters. The --xx and --vv
options are turned off. If there are no _a_r_gs, the posi-
tional parameters remain unchanged.
The options are off by default unless otherwise noted. Using +
rather than - causes these options to be turned off. The
options can also be specified as arguments to an invocation of
the shell. The current set of options may be found in $$--. The
return status is always true unless an invalid option is encoun-
tered.
sshhiifftt [_n]
The positional parameters from _n+1 ... are renamed to $$11 ........
Parameters represented by the numbers $$## down to $$##-_n+1 are
unset. _n must be a non-negative number less than or equal to
$$##. If _n is 0, no parameters are changed. If _n is not given,
it is assumed to be 1. If _n is greater than $$##, the positional
parameters are not changed. The return status is greater than
zero if _n is greater than $$## or less than zero; otherwise 0.
sshhoopptt [--ppqqssuu] [--oo] [_o_p_t_n_a_m_e ...]
Toggle the values of variables controlling optional shell behav-
ior. With no options, or with the --pp option, a list of all set-
table options is displayed, with an indication of whether or not
each is set. The --pp option causes output to be displayed in a
form that may be reused as input. Other options have the fol-
lowing meanings:
--ss Enable (set) each _o_p_t_n_a_m_e.
--uu Disable (unset) each _o_p_t_n_a_m_e.
--qq Suppresses normal output (quiet mode); the return status
indicates whether the _o_p_t_n_a_m_e is set or unset. If multi-
ple _o_p_t_n_a_m_e arguments are given with --qq, the return sta-
tus is zero if all _o_p_t_n_a_m_e_s are enabled; non-zero other-
wise.
--oo Restricts the values of _o_p_t_n_a_m_e to be those defined for
the --oo option to the sseett builtin.
If either --ss or --uu is used with no _o_p_t_n_a_m_e arguments, the dis-
play is limited to those options which are set or unset, respec-
tively. Unless otherwise noted, the sshhoopptt options are disabled
(unset) by default.
The return status when listing options is zero if all _o_p_t_n_a_m_e_s
are enabled, non-zero otherwise. When setting or unsetting
options, the return status is zero unless an _o_p_t_n_a_m_e is not a
valid shell option.
The list of sshhoopptt options is:
ccddaabbllee__vvaarrss
If set, an argument to the ccdd builtin command that is
not a directory is assumed to be the name of a variable
whose value is the directory to change to.
ccddssppeellll If set, minor errors in the spelling of a directory com-
ponent in a ccdd command will be corrected. The errors
checked for are transposed characters, a missing charac-
ter, and one character too many. If a correction is
found, the corrected file name is printed, and the com-
mand proceeds. This option is only used by interactive
shells.
cchheecckkhhaasshh
If set, bbaasshh checks that a command found in the hash ta-
ble exists before trying to execute it. If a hashed
command no longer exists, a normal path search is per-
formed.
cchheecckkwwiinnssiizzee
If set, bbaasshh checks the window size after each command
and, if necessary, updates the values of LLIINNEESS and CCOOLL--
UUMMNNSS.
ccmmddhhiisstt If set, bbaasshh attempts to save all lines of a multiple-
line command in the same history entry. This allows
easy re-editing of multi-line commands.
ddoottgglloobb If set, bbaasshh includes filenames beginning with a `.' in
the results of pathname expansion.
eexxeeccffaaiill
If set, a non-interactive shell will not exit if it can-
not execute the file specified as an argument to the
eexxeecc builtin command. An interactive shell does not
exit if eexxeecc fails.
eexxppaanndd__aalliiaasseess
If set, aliases are expanded as described above under
AALLIIAASSEESS. This option is enabled by default for interac-
tive shells.
eexxttddeebbuugg
If set, behavior intended for use by debuggers is
enabled:
11.. The --FF option to the ddeeccllaarree builtin displays the
source file name and line number corresponding to
each function name supplied as an argument.
22.. If the command run by the DDEEBBUUGG trap returns a
non-zero value, the next command is skipped and
not executed.
33.. If the command run by the DDEEBBUUGG trap returns a
value of 2, and the shell is executing in a sub-
routine (a shell function or a shell script exe-
cuted by the .. or ssoouurrccee builtins), a call to
rreettuurrnn is simulated.
44.. BBAASSHH__AARRGGCC and BBAASSHH__AARRGGVV are updated as described
in their descriptions above.
55.. Function tracing is enabled: command substitu-
tion, shell functions, and subshells invoked with
(( _c_o_m_m_a_n_d )) inherit the DDEEBBUUGG and RREETTUURRNN traps.
66.. Error tracing is enabled: command substitution,
shell functions, and subshells invoked with ((
_c_o_m_m_a_n_d )) inherit the EERRRROORR trap.
eexxttgglloobb If set, the extended pattern matching features described
above under PPaatthhnnaammee EExxppaannssiioonn are enabled.
eexxttqquuoottee
If set, $$'_s_t_r_i_n_g' and $$"_s_t_r_i_n_g" quoting is performed
within $${{_p_a_r_a_m_e_t_e_r}} expansions enclosed in double
quotes. This option is enabled by default.
ffaaiillgglloobb
If set, patterns which fail to match filenames during
pathname expansion result in an expansion error.
ffoorrccee__ffiiggnnoorree
If set, the suffixes specified by the FFIIGGNNOORREE shell
variable cause words to be ignored when performing word
completion even if the ignored words are the only possi-
ble completions. See SSHHEELLLL VVAARRIIAABBLLEESS above for a
description of FFIIGGNNOORREE. This option is enabled by
default.
ggnnuu__eerrrrffmmtt
If set, shell error messages are written in the standard
GNU error message format.
hhiissttaappppeenndd
If set, the history list is appended to the file named
by the value of the HHIISSTTFFIILLEE variable when the shell
exits, rather than overwriting the file.
hhiissttrreeeeddiitt
If set, and rreeaaddlliinnee is being used, a user is given the
opportunity to re-edit a failed history substitution.
hhiissttvveerriiffyy
If set, and rreeaaddlliinnee is being used, the results of his-
tory substitution are not immediately passed to the
shell parser. Instead, the resulting line is loaded
into the rreeaaddlliinnee editing buffer, allowing further modi-
fication.
hhoossttccoommpplleettee
If set, and rreeaaddlliinnee is being used, bbaasshh will attempt to
perform hostname completion when a word containing a @@
is being completed (see CCoommpplleettiinngg under RREEAADDLLIINNEE
above). This is enabled by default.
hhuuppoonneexxiitt
If set, bbaasshh will send SSIIGGHHUUPP to all jobs when an inter-
active login shell exits.
iinntteerraaccttiivvee__ccoommmmeennttss
If set, allow a word beginning with ## to cause that word
and all remaining characters on that line to be ignored
in an interactive shell (see CCOOMMMMEENNTTSS above). This
option is enabled by default.
lliitthhiisstt If set, and the ccmmddhhiisstt option is enabled, multi-line
commands are saved to the history with embedded newlines
rather than using semicolon separators where possible.
llooggiinn__sshheellll
The shell sets this option if it is started as a login
shell (see IINNVVOOCCAATTIIOONN above). The value may not be
changed.
mmaaiillwwaarrnn
If set, and a file that bbaasshh is checking for mail has
been accessed since the last time it was checked, the
message ``The mail in _m_a_i_l_f_i_l_e has been read'' is dis-
played.
nnoo__eemmppttyy__ccmmdd__ccoommpplleettiioonn
If set, and rreeaaddlliinnee is being used, bbaasshh will not
attempt to search the PPAATTHH for possible completions when
completion is attempted on an empty line.
nnooccaasseegglloobb
If set, bbaasshh matches filenames in a case-insensitive
fashion when performing pathname expansion (see PPaatthhnnaammee
EExxppaannssiioonn above).
nnooccaasseemmaattcchh
If set, bbaasshh matches patterns in a case-insensitive
fashion when performing matching while executing ccaassee or
[[[[ conditional commands.
nnuullllgglloobb
If set, bbaasshh allows patterns which match no files (see
PPaatthhnnaammee EExxppaannssiioonn above) to expand to a null string,
rather than themselves.
pprrooggccoommpp
If set, the programmable completion facilities (see PPrroo--
ggrraammmmaabbllee CCoommpplleettiioonn above) are enabled. This option is
enabled by default.
pprroommppttvvaarrss
If set, prompt strings undergo parameter expansion, com-
mand substitution, arithmetic expansion, and quote
removal after being expanded as described in PPRROOMMPPTTIINNGG
above. This option is enabled by default.
rreessttrriicctteedd__sshheellll
The shell sets this option if it is started in
restricted mode (see RREESSTTRRIICCTTEEDD SSHHEELLLL below). The value
may not be changed. This is not reset when the startup
files are executed, allowing the startup files to dis-
cover whether or not a shell is restricted.
sshhiifftt__vveerrbboossee
If set, the sshhiifftt builtin prints an error message when
the shift count exceeds the number of positional parame-
ters.
ssoouurrcceeppaatthh
If set, the ssoouurrccee (..) builtin uses the value of PPAATTHH to
find the directory containing the file supplied as an
argument. This option is enabled by default.
xxppgg__eecchhoo
If set, the eecchhoo builtin expands backslash-escape
sequences by default.
ssuussppeenndd [--ff]
Suspend the execution of this shell until it receives a SSIIGGCCOONNTT
signal. The --ff option says not to complain if this is a login
shell; just suspend anyway. The return status is 0 unless the
shell is a login shell and --ff is not supplied, or if job control
is not enabled.
tteesstt _e_x_p_r
[[ _e_x_p_r ]]
Return a status of 0 or 1 depending on the evaluation of the
conditional expression _e_x_p_r. Each operator and operand must be
a separate argument. Expressions are composed of the primaries
described above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS. tteesstt does not
accept any options, nor does it accept and ignore an argument of
---- as signifying the end of options.
Expressions may be combined using the following operators,
listed in decreasing order of precedence.
!! _e_x_p_r True if _e_x_p_r is false.
(( _e_x_p_r ))
Returns the value of _e_x_p_r. This may be used to override
the normal precedence of operators.
_e_x_p_r_1 -aa _e_x_p_r_2
True if both _e_x_p_r_1 and _e_x_p_r_2 are true.
_e_x_p_r_1 -oo _e_x_p_r_2
True if either _e_x_p_r_1 or _e_x_p_r_2 is true.
tteesstt and [[ evaluate conditional expressions using a set of rules
based on the number of arguments.
0 arguments
The expression is false.
1 argument
The expression is true if and only if the argument is not
null.
2 arguments
If the first argument is !!, the expression is true if and
only if the second argument is null. If the first argu-
ment is one of the unary conditional operators listed
above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the expression is
true if the unary test is true. If the first argument is
not a valid unary conditional operator, the expression is
false.
3 arguments
If the second argument is one of the binary conditional
operators listed above under CCOONNDDIITTIIOONNAALL EEXXPPRREESSSSIIOONNSS, the
result of the expression is the result of the binary test
using the first and third arguments as operands. If the
first argument is !!, the value is the negation of the
two-argument test using the second and third arguments.
If the first argument is exactly (( and the third argument
is exactly )), the result is the one-argument test of the
second argument. Otherwise, the expression is false.
The --aa and --oo operators are considered binary operators
in this case.
4 arguments
If the first argument is !!, the result is the negation of
the three-argument expression composed of the remaining
arguments. Otherwise, the expression is parsed and eval-
uated according to precedence using the rules listed
above.
5 or more arguments
The expression is parsed and evaluated according to
precedence using the rules listed above.
ttiimmeess Print the accumulated user and system times for the shell and
for processes run from the shell. The return status is 0.
ttrraapp [--llpp] [[_a_r_g] _s_i_g_s_p_e_c ...]
The command _a_r_g is to be read and executed when the shell
receives signal(s) _s_i_g_s_p_e_c. If _a_r_g is absent (and there is a
single _s_i_g_s_p_e_c) or --, each specified signal is reset to its
original disposition (the value it had upon entrance to the
shell). If _a_r_g is the null string the signal specified by each
_s_i_g_s_p_e_c is ignored by the shell and by the commands it invokes.
If _a_r_g is not present and --pp has been supplied, then the trap
commands associated with each _s_i_g_s_p_e_c are displayed. If no
arguments are supplied or if only --pp is given, ttrraapp prints the
list of commands associated with each signal. The --ll option
causes the shell to print a list of signal names and their cor-
responding numbers. Each _s_i_g_s_p_e_c is either a signal name
defined in <_s_i_g_n_a_l_._h>, or a signal number. Signal names are
case insensitive and the SIG prefix is optional. If a _s_i_g_s_p_e_c
is EEXXIITT (0) the command _a_r_g is executed on exit from the shell.
If a _s_i_g_s_p_e_c is DDEEBBUUGG, the command _a_r_g is executed before every
_s_i_m_p_l_e _c_o_m_m_a_n_d, _f_o_r command, _c_a_s_e command, _s_e_l_e_c_t command, every
arithmetic _f_o_r command, and before the first command executes in
a shell function (see SSHHEELLLL GGRRAAMMMMAARR above). Refer to the
description of the eexxttddeebbuugg option to the sshhoopptt builtin for
details of its effect on the DDEEBBUUGG trap. If a _s_i_g_s_p_e_c is EERRRR,
the command _a_r_g is executed whenever a simple command has a
non-zero exit status, subject to the following conditions. The
EERRRR trap is not executed if the failed command is part of the
command list immediately following a wwhhiillee or uunnttiill keyword,
part of the test in an _i_f statement, part of a &&&& or |||| list, or
if the command's return value is being inverted via !!. These
are the same conditions obeyed by the eerrrreexxiitt option. If a
_s_i_g_s_p_e_c is RREETTUURRNN, the command _a_r_g is executed each time a shell
function or a script executed with the .. or ssoouurrccee builtins fin-
ishes executing. Signals ignored upon entry to the shell cannot
be trapped or reset. Trapped signals that are not being ignored
are reset to their original values in a child process when it is
created. The return status is false if any _s_i_g_s_p_e_c is invalid;
otherwise ttrraapp returns true.
ttyyppee [--aaffttppPP] _n_a_m_e [_n_a_m_e ...]
With no options, indicate how each _n_a_m_e would be interpreted if
used as a command name. If the --tt option is used, ttyyppee prints a
string which is one of _a_l_i_a_s, _k_e_y_w_o_r_d, _f_u_n_c_t_i_o_n, _b_u_i_l_t_i_n, or
_f_i_l_e if _n_a_m_e is an alias, shell reserved word, function,
builtin, or disk file, respectively. If the _n_a_m_e is not found,
then nothing is printed, and an exit status of false is
returned. If the --pp option is used, ttyyppee either returns the
name of the disk file that would be executed if _n_a_m_e were speci-
fied as a command name, or nothing if ``type -t name'' would not
return _f_i_l_e. The --PP option forces a PPAATTHH search for each _n_a_m_e,
even if ``type -t name'' would not return _f_i_l_e. If a command is
hashed, --pp and --PP print the hashed value, not necessarily the
file that appears first in PPAATTHH. If the --aa option is used, ttyyppee
prints all of the places that contain an executable named _n_a_m_e.
This includes aliases and functions, if and only if the --pp
option is not also used. The table of hashed commands is not
consulted when using --aa. The --ff option suppresses shell func-
tion lookup, as with the ccoommmmaanndd builtin. ttyyppee returns true if
any of the arguments are found, false if none are found.
uulliimmiitt [--SSHHaaccddeeffiillmmnnppqqrrssttuuvvxx [_l_i_m_i_t]]
Provides control over the resources available to the shell and
to processes started by it, on systems that allow such control.
The --HH and --SS options specify that the hard or soft limit is set
for the given resource. A hard limit cannot be increased once
it is set; a soft limit may be increased up to the value of the
hard limit. If neither --HH nor --SS is specified, both the soft
and hard limits are set. The value of _l_i_m_i_t can be a number in
the unit specified for the resource or one of the special values
hhaarrdd, ssoofftt, or uunnlliimmiitteedd, which stand for the current hard
limit, the current soft limit, and no limit, respectively. If
_l_i_m_i_t is omitted, the current value of the soft limit of the
resource is printed, unless the --HH option is given. When more
than one resource is specified, the limit name and unit are
printed before the value. Other options are interpreted as fol-
lows:
--aa All current limits are reported
--cc The maximum size of core files created
--dd The maximum size of a process's data segment
--ee The maximum scheduling priority ("nice")
--ff The maximum size of files written by the shell and its
children
--ii The maximum number of pending signals
--ll The maximum size that may be locked into memory
--mm The maximum resident set size
--nn The maximum number of open file descriptors (most systems
do not allow this value to be set)
--pp The pipe size in 512-byte blocks (this may not be set)
--qq The maximum number of bytes in POSIX message queues
--rr The maximum real-time scheduling priority
--ss The maximum stack size
--tt The maximum amount of cpu time in seconds
--uu The maximum number of processes available to a single
user
--vv The maximum amount of virtual memory available to the
shell
--xx The maximum number of file locks
If _l_i_m_i_t is given, it is the new value of the specified resource
(the --aa option is display only). If no option is given, then --ff
is assumed. Values are in 1024-byte increments, except for --tt,
which is in seconds, --pp, which is in units of 512-byte blocks,
and --nn and --uu, which are unscaled values. The return status is
0 unless an invalid option or argument is supplied, or an error
occurs while setting a new limit.
uummaasskk [--pp] [--SS] [_m_o_d_e]
The user file-creation mask is set to _m_o_d_e. If _m_o_d_e begins with
a digit, it is interpreted as an octal number; otherwise it is
interpreted as a symbolic mode mask similar to that accepted by
_c_h_m_o_d(1). If _m_o_d_e is omitted, the current value of the mask is
printed. The --SS option causes the mask to be printed in sym-
bolic form; the default output is an octal number. If the --pp
option is supplied, and _m_o_d_e is omitted, the output is in a form
that may be reused as input. The return status is 0 if the mode
was successfully changed or if no _m_o_d_e argument was supplied,
and false otherwise.
uunnaalliiaass [-aa] [_n_a_m_e ...]
Remove each _n_a_m_e from the list of defined aliases. If --aa is
supplied, all alias definitions are removed. The return value
is true unless a supplied _n_a_m_e is not a defined alias.
uunnsseett [-ffvv] [_n_a_m_e ...]
For each _n_a_m_e, remove the corresponding variable or function.
If no options are supplied, or the --vv option is given, each _n_a_m_e
refers to a shell variable. Read-only variables may not be
unset. If --ff is specified, each _n_a_m_e refers to a shell func-
tion, and the function definition is removed. Each unset vari-
able or function is removed from the environment passed to sub-
sequent commands. If any of RRAANNDDOOMM, SSEECCOONNDDSS, LLIINNEENNOO, HHIISSTTCCMMDD,
FFUUNNCCNNAAMMEE, GGRROOUUPPSS, or DDIIRRSSTTAACCKK are unset, they lose their special
properties, even if they are subsequently reset. The exit sta-
tus is true unless a _n_a_m_e is readonly.
wwaaiitt [_n _._._.]
Wait for each specified process and return its termination sta-
tus. Each _n may be a process ID or a job specification; if a
job spec is given, all processes in that job's pipeline are
waited for. If _n is not given, all currently active child pro-
cesses are waited for, and the return status is zero. If _n
specifies a non-existent process or job, the return status is
127. Otherwise, the return status is the exit status of the
last process or job waited for.
SSEEEE AALLSSOO
bash(1), sh(1)
GNU Bash-3.0 2004 Apr 20 BASH_BUILTINS(1)