bash: Bash Builtins
1
1 4.2 Bash Builtin Commands
1 =========================
1
1 This section describes builtin commands which are unique to or have been
1 extended in Bash. Some of these commands are specified in the POSIX
1 standard.
1
1 'alias'
1 alias [-p] [NAME[=VALUE] ...]
1
1 Without arguments or with the '-p' option, 'alias' prints the list
1 of aliases on the standard output in a form that allows them to be
1 reused as input. If arguments are supplied, an alias is defined
1 for each NAME whose VALUE is given. If no VALUE is given, the name
11 and value of the alias is printed. Aliases are described in ⇒
Aliases.
1
1 'bind'
1 bind [-m KEYMAP] [-lpsvPSVX]
1 bind [-m KEYMAP] [-q FUNCTION] [-u FUNCTION] [-r KEYSEQ]
1 bind [-m KEYMAP] -f FILENAME
1 bind [-m KEYMAP] -x KEYSEQ:SHELL-COMMAND
1 bind [-m KEYMAP] KEYSEQ:FUNCTION-NAME
1 bind [-m KEYMAP] KEYSEQ:READLINE-COMMAND
1
1 Display current Readline (⇒Command Line Editing) key and
1 function bindings, bind a key sequence to a Readline function or
1 macro, or set a Readline variable. Each non-option argument is a
11 command as it would appear in a Readline initialization file (⇒
Readline Init File), but each binding or command must be passed
1 as a separate argument; e.g., '"\C-x\C-r":re-read-init-file'.
1
1 Options, if supplied, have the following meanings:
1
1 '-m KEYMAP'
1 Use KEYMAP as the keymap to be affected by the subsequent
1 bindings. Acceptable KEYMAP names are 'emacs',
1 'emacs-standard', 'emacs-meta', 'emacs-ctlx', 'vi', 'vi-move',
1 'vi-command', and 'vi-insert'. 'vi' is equivalent to
1 'vi-command' ('vi-move' is also a synonym); 'emacs' is
1 equivalent to 'emacs-standard'.
1
1 '-l'
1 List the names of all Readline functions.
1
1 '-p'
1 Display Readline function names and bindings in such a way
1 that they can be used as input or in a Readline initialization
1 file.
1
1 '-P'
1 List current Readline function names and bindings.
1
1 '-v'
1 Display Readline variable names and values in such a way that
1 they can be used as input or in a Readline initialization
1 file.
1
1 '-V'
1 List current Readline variable names and values.
1
1 '-s'
1 Display Readline key sequences bound to macros and the strings
1 they output in such a way that they can be used as input or in
1 a Readline initialization file.
1
1 '-S'
1 Display Readline key sequences bound to macros and the strings
1 they output.
1
1 '-f FILENAME'
1 Read key bindings from FILENAME.
1
1 '-q FUNCTION'
1 Query about which keys invoke the named FUNCTION.
1
1 '-u FUNCTION'
1 Unbind all keys bound to the named FUNCTION.
1
1 '-r KEYSEQ'
1 Remove any current binding for KEYSEQ.
1
1 '-x KEYSEQ:SHELL-COMMAND'
1 Cause SHELL-COMMAND to be executed whenever KEYSEQ is entered.
1 When SHELL-COMMAND is executed, the shell sets the
1 'READLINE_LINE' variable to the contents of the Readline line
1 buffer and the 'READLINE_POINT' variable to the current
1 location of the insertion point. If the executed command
1 changes the value of 'READLINE_LINE' or 'READLINE_POINT',
1 those new values will be reflected in the editing state.
1
1 '-X'
1 List all key sequences bound to shell commands and the
1 associated commands in a format that can be reused as input.
1
1 The return status is zero unless an invalid option is supplied or
1 an error occurs.
1
1 'builtin'
1 builtin [SHELL-BUILTIN [ARGS]]
1
1 Run a shell builtin, passing it ARGS, and return its exit status.
1 This is useful when defining a shell function with the same name as
1 a shell builtin, retaining the functionality of the builtin within
1 the function. The return status is non-zero if SHELL-BUILTIN is
1 not a shell builtin command.
1
1 'caller'
1 caller [EXPR]
1
1 Returns the context of any active subroutine call (a shell function
1 or a script executed with the '.' or 'source' builtins).
1
1 Without EXPR, 'caller' displays the line number and source filename
1 of the current subroutine call. If a non-negative integer is
1 supplied as EXPR, 'caller' displays the line number, subroutine
1 name, and source file corresponding to that position in the current
1 execution call stack. This extra information may be used, for
1 example, to print a stack trace. The current frame is frame 0.
1
1 The return value is 0 unless the shell is not executing a
1 subroutine call or EXPR does not correspond to a valid position in
1 the call stack.
1
1 'command'
1 command [-pVv] COMMAND [ARGUMENTS ...]
1
1 Runs COMMAND with ARGUMENTS ignoring any shell function named
1 COMMAND. Only shell builtin commands or commands found by
1 searching the 'PATH' are executed. If there is a shell function
1 named 'ls', running 'command ls' within the function will execute
1 the external command 'ls' instead of calling the function
1 recursively. The '-p' option means to use a default value for
1 'PATH' that is guaranteed to find all of the standard utilities.
1 The return status in this case is 127 if COMMAND cannot be found or
1 an error occurred, and the exit status of COMMAND otherwise.
1
1 If either the '-V' or '-v' option is supplied, a description of
1 COMMAND is printed. The '-v' option causes a single word
1 indicating the command or file name used to invoke COMMAND to be
1 displayed; the '-V' option produces a more verbose description. In
1 this case, the return status is zero if COMMAND is found, and
1 non-zero if not.
1
1 'declare'
1 declare [-aAfFgilnrtux] [-p] [NAME[=VALUE] ...]
1
1 Declare variables and give them attributes. If no NAMEs are given,
1 then display the values of variables instead.
1
1 The '-p' option will display the attributes and values of each
1 NAME. When '-p' is used with NAME arguments, additional options,
1 other than '-f' and '-F', are ignored.
1
1 When '-p' is supplied without NAME arguments, 'declare' will
1 display the attributes and values of all variables having the
1 attributes specified by the additional options. If no other
1 options are supplied with '-p', 'declare' will display the
1 attributes and values of all shell variables. The '-f' option will
1 restrict the display to shell functions.
1
1 The '-F' option inhibits the display of function definitions; only
1 the function name and attributes are printed. If the 'extdebug'
1 shell option is enabled using 'shopt' (⇒The Shopt Builtin),
1 the source file name and line number where each NAME is defined are
1 displayed as well. '-F' implies '-f'.
1
1 The '-g' option forces variables to be created or modified at the
1 global scope, even when 'declare' is executed in a shell function.
1 It is ignored in all other cases.
1
1 The following options can be used to restrict output to variables
1 with the specified attributes or to give variables attributes:
1
1 '-a'
1 Each NAME is an indexed array variable (⇒Arrays).
1
1 '-A'
1 Each NAME is an associative array variable (⇒Arrays).
1
1 '-f'
1 Use function names only.
1
1 '-i'
1 The variable is to be treated as an integer; arithmetic
1 evaluation (⇒Shell Arithmetic) is performed when the
1 variable is assigned a value.
1
1 '-l'
1 When the variable is assigned a value, all upper-case
1 characters are converted to lower-case. The upper-case
1 attribute is disabled.
1
1 '-n'
1 Give each NAME the NAMEREF attribute, making it a name
1 reference to another variable. That other variable is defined
1 by the value of NAME. All references, assignments, and
1 attribute modifications to NAME, except for those using or
1 changing the '-n' attribute itself, are performed on the
1 variable referenced by NAME's value. The nameref attribute
1 cannot be applied to array variables.
1
1 '-r'
1 Make NAMEs readonly. These names cannot then be assigned
1 values by subsequent assignment statements or unset.
1
1 '-t'
1 Give each NAME the 'trace' attribute. Traced functions
1 inherit the 'DEBUG' and 'RETURN' traps from the calling shell.
1 The trace attribute has no special meaning for variables.
1
1 '-u'
1 When the variable is assigned a value, all lower-case
1 characters are converted to upper-case. The lower-case
1 attribute is disabled.
1
1 '-x'
1 Mark each NAME for export to subsequent commands via the
1 environment.
1
1 Using '+' instead of '-' turns off the attribute instead, with the
1 exceptions that '+a' may not be used to destroy an array variable
1 and '+r' will not remove the readonly attribute. When used in a
1 function, 'declare' makes each NAME local, as with the 'local'
1 command, unless the '-g' option is used. If a variable name is
1 followed by =VALUE, the value of the variable is set to VALUE.
1
1 When using '-a' or '-A' and the compound assignment syntax to
1 create array variables, additional attributes do not take effect
1 until subsequent assignments.
1
1 The return status is zero unless an invalid option is encountered,
1 an attempt is made to define a function using '-f foo=bar', an
1 attempt is made to assign a value to a readonly variable, an
1 attempt is made to assign a value to an array variable without
1 using the compound assignment syntax (⇒Arrays), one of the
1 NAMES is not a valid shell variable name, an attempt is made to
1 turn off readonly status for a readonly variable, an attempt is
1 made to turn off array status for an array variable, or an attempt
1 is made to display a non-existent function with '-f'.
1
1 'echo'
1 echo [-neE] [ARG ...]
1
1 Output the ARGs, separated by spaces, terminated with a newline.
1 The return status is 0 unless a write error occurs. If '-n' is
1 specified, the trailing newline is suppressed. If the '-e' option
1 is given, interpretation of the following backslash-escaped
1 characters is enabled. The '-E' option disables the interpretation
1 of these escape characters, even on systems where they are
1 interpreted by default. The 'xpg_echo' shell option may be used to
1 dynamically determine whether or not 'echo' expands these escape
1 characters by default. 'echo' does not interpret '--' to mean the
1 end of options.
1
1 'echo' interprets the following escape sequences:
1 '\a'
1 alert (bell)
1 '\b'
1 backspace
1 '\c'
1 suppress further output
1 '\e'
1 '\E'
1 escape
1 '\f'
1 form feed
1 '\n'
1 new line
1 '\r'
1 carriage return
1 '\t'
1 horizontal tab
1 '\v'
1 vertical tab
1 '\\'
1 backslash
1 '\0NNN'
1 the eight-bit character whose value is the octal value NNN
1 (zero to three octal digits)
1 '\xHH'
1 the eight-bit character whose value is the hexadecimal value
1 HH (one or two hex digits)
1 '\uHHHH'
1 the Unicode (ISO/IEC 10646) character whose value is the
1 hexadecimal value HHHH (one to four hex digits)
1 '\UHHHHHHHH'
1 the Unicode (ISO/IEC 10646) character whose value is the
1 hexadecimal value HHHHHHHH (one to eight hex digits)
1
1 'enable'
1 enable [-a] [-dnps] [-f FILENAME] [NAME ...]
1
1 Enable and disable builtin shell commands. Disabling a builtin
1 allows a disk command which has the same name as a shell builtin to
1 be executed without specifying a full pathname, even though the
1 shell normally searches for builtins before disk commands. If '-n'
1 is used, the NAMEs become disabled. Otherwise NAMEs are enabled.
1 For example, to use the 'test' binary found via '$PATH' instead of
1 the shell builtin version, type 'enable -n test'.
1
1 If the '-p' option is supplied, or no NAME arguments appear, a list
1 of shell builtins is printed. With no other arguments, the list
1 consists of all enabled shell builtins. The '-a' option means to
1 list each builtin with an indication of whether or not it is
1 enabled.
1
1 The '-f' option means to load the new builtin command NAME from
1 shared object FILENAME, on systems that support dynamic loading.
1 The '-d' option will delete a builtin loaded with '-f'.
1
1 If there are no options, a list of the shell builtins is displayed.
1 The '-s' option restricts 'enable' to the POSIX special builtins.
1 If '-s' is used with '-f', the new builtin becomes a special
1 builtin (⇒Special Builtins).
1
1 The return status is zero unless a NAME is not a shell builtin or
1 there is an error loading a new builtin from a shared object.
1
1 'help'
1 help [-dms] [PATTERN]
1
1 Display helpful information about builtin commands. If PATTERN is
1 specified, 'help' gives detailed help on all commands matching
1 PATTERN, otherwise a list of the builtins is printed.
1
1 Options, if supplied, have the following meanings:
1
1 '-d'
1 Display a short description of each PATTERN
1 '-m'
1 Display the description of each PATTERN in a manpage-like
1 format
1 '-s'
1 Display only a short usage synopsis for each PATTERN
1
1 The return status is zero unless no command matches PATTERN.
1
1 'let'
1 let EXPRESSION [EXPRESSION ...]
1
1 The 'let' builtin allows arithmetic to be performed on shell
1 variables. Each EXPRESSION is evaluated according to the rules
1 given below in ⇒Shell Arithmetic. If the last EXPRESSION
1 evaluates to 0, 'let' returns 1; otherwise 0 is returned.
1
1 'local'
1 local [OPTION] NAME[=VALUE] ...
1
1 For each argument, a local variable named NAME is created, and
1 assigned VALUE. The OPTION can be any of the options accepted by
1 'declare'. 'local' can only be used within a function; it makes
1 the variable NAME have a visible scope restricted to that function
1 and its children. If NAME is '-', the set of shell options is made
1 local to the function in which 'local' is invoked: shell options
1 changed using the 'set' builtin inside the function are restored to
1 their original values when the function returns. The return status
1 is zero unless 'local' is used outside a function, an invalid NAME
1 is supplied, or NAME is a readonly variable.
1
1 'logout'
1 logout [N]
1
1 Exit a login shell, returning a status of N to the shell's parent.
1
1 'mapfile'
1 mapfile [-d DELIM] [-n COUNT] [-O ORIGIN] [-s COUNT] [-t] [-u FD]
1 [-C CALLBACK] [-c QUANTUM] [ARRAY]
1
1 Read lines from the standard input into the indexed array variable
1 ARRAY, or from file descriptor FD if the '-u' option is supplied.
1 The variable 'MAPFILE' is the default ARRAY. Options, if supplied,
1 have the following meanings:
1
1 '-d'
1 The first character of DELIM is used to terminate each input
1 line, rather than newline.
1 '-n'
1 Copy at most COUNT lines. If COUNT is 0, all lines are
1 copied.
1 '-O'
1 Begin assigning to ARRAY at index ORIGIN. The default index
1 is 0.
1 '-s'
1 Discard the first COUNT lines read.
1 '-t'
1 Remove a trailing DELIM (default newline) from each line read.
1 '-u'
1 Read lines from file descriptor FD instead of the standard
1 input.
1 '-C'
1 Evaluate CALLBACK each time QUANTUMP lines are read. The '-c'
1 option specifies QUANTUM.
1 '-c'
1 Specify the number of lines read between each call to
1 CALLBACK.
1
1 If '-C' is specified without '-c', the default quantum is 5000.
1 When CALLBACK is evaluated, it is supplied the index of the next
1 array element to be assigned and the line to be assigned to that
1 element as additional arguments. CALLBACK is evaluated after the
1 line is read but before the array element is assigned.
1
1 If not supplied with an explicit origin, 'mapfile' will clear ARRAY
1 before assigning to it.
1
1 'mapfile' returns successfully unless an invalid option or option
1 argument is supplied, ARRAY is invalid or unassignable, or ARRAY is
1 not an indexed array.
1
1 'printf'
1 printf [-v VAR] FORMAT [ARGUMENTS]
1
1 Write the formatted ARGUMENTS to the standard output under the
1 control of the FORMAT. The '-v' option causes the output to be
1 assigned to the variable VAR rather than being printed to the
1 standard output.
1
1 The FORMAT is a character string which contains three types of
1 objects: plain characters, which are simply copied to standard
1 output, character escape sequences, which are converted and copied
1 to the standard output, and format specifications, each of which
1 causes printing of the next successive ARGUMENT. In addition to
1 the standard 'printf(1)' formats, 'printf' interprets the following
1 extensions:
1
1 '%b'
1 Causes 'printf' to expand backslash escape sequences in the
11 corresponding ARGUMENT in the same way as 'echo -e' (⇒
Bash Builtins).
1 '%q'
1 Causes 'printf' to output the corresponding ARGUMENT in a
1 format that can be reused as shell input.
1 '%(DATEFMT)T'
1 Causes 'printf' to output the date-time string resulting from
1 using DATEFMT as a format string for 'strftime'(3). The
1 corresponding ARGUMENT is an integer representing the number
1 of seconds since the epoch. Two special argument values may
1 be used: -1 represents the current time, and -2 represents the
1 time the shell was invoked. If no argument is specified,
1 conversion behaves as if -1 had been given. This is an
1 exception to the usual 'printf' behavior.
1
1 Arguments to non-string format specifiers are treated as C language
1 constants, except that a leading plus or minus sign is allowed, and
1 if the leading character is a single or double quote, the value is
1 the ASCII value of the following character.
1
1 The FORMAT is reused as necessary to consume all of the ARGUMENTS.
1 If the FORMAT requires more ARGUMENTS than are supplied, the extra
1 format specifications behave as if a zero value or null string, as
1 appropriate, had been supplied. The return value is zero on
1 success, non-zero on failure.
1
1 'read'
1 read [-ers] [-a ANAME] [-d DELIM] [-i TEXT] [-n NCHARS]
1 [-N NCHARS] [-p PROMPT] [-t TIMEOUT] [-u FD] [NAME ...]
1
1 One line is read from the standard input, or from the file
1 descriptor FD supplied as an argument to the '-u' option, split
1 into words as described above in ⇒Word Splitting, and the
1 first word is assigned to the first NAME, the second word to the
1 second NAME, and so on. If there are more words than names, the
1 remaining words and their intervening delimiters are assigned to
1 the last NAME. If there are fewer words read from the input stream
1 than names, the remaining names are assigned empty values. The
1 characters in the value of the 'IFS' variable are used to split the
1 line into words using the same rules the shell uses for expansion
1 (described above in ⇒Word Splitting). The backslash
1 character '\' may be used to remove any special meaning for the
1 next character read and for line continuation. If no names are
1 supplied, the line read is assigned to the variable 'REPLY'. The
1 exit status is zero, unless end-of-file is encountered, 'read'
1 times out (in which case the status is greater than 128), a
1 variable assignment error (such as assigning to a readonly
1 variable) occurs, or an invalid file descriptor is supplied as the
1 argument to '-u'.
1
1 Options, if supplied, have the following meanings:
1
1 '-a ANAME'
1 The words are assigned to sequential indices of the array
1 variable ANAME, starting at 0. All elements are removed from
1 ANAME before the assignment. Other NAME arguments are
1 ignored.
1
1 '-d DELIM'
1 The first character of DELIM is used to terminate the input
1 line, rather than newline.
1
1 '-e'
1 Readline (⇒Command Line Editing) is used to obtain the
1 line. Readline uses the current (or default, if line editing
1 was not previously active) editing settings.
1
1 '-i TEXT'
1 If Readline is being used to read the line, TEXT is placed
1 into the editing buffer before editing begins.
1
1 '-n NCHARS'
1 'read' returns after reading NCHARS characters rather than
1 waiting for a complete line of input, but honors a delimiter
1 if fewer than NCHARS characters are read before the delimiter.
1
1 '-N NCHARS'
1 'read' returns after reading exactly NCHARS characters rather
1 than waiting for a complete line of input, unless EOF is
1 encountered or 'read' times out. Delimiter characters
1 encountered in the input are not treated specially and do not
1 cause 'read' to return until NCHARS characters are read. The
1 result is not split on the characters in 'IFS'; the intent is
1 that the variable is assigned exactly the characters read
1 (with the exception of backslash; see the '-r' option below).
1
1 '-p PROMPT'
1 Display PROMPT, without a trailing newline, before attempting
1 to read any input. The prompt is displayed only if input is
1 coming from a terminal.
1
1 '-r'
1 If this option is given, backslash does not act as an escape
1 character. The backslash is considered to be part of the
1 line. In particular, a backslash-newline pair may not be used
1 as a line continuation.
1
1 '-s'
1 Silent mode. If input is coming from a terminal, characters
1 are not echoed.
1
1 '-t TIMEOUT'
1 Cause 'read' to time out and return failure if a complete line
1 of input (or a specified number of characters) is not read
1 within TIMEOUT seconds. TIMEOUT may be a decimal number with
1 a fractional portion following the decimal point. This option
1 is only effective if 'read' is reading input from a terminal,
1 pipe, or other special file; it has no effect when reading
1 from regular files. If 'read' times out, 'read' saves any
1 partial input read into the specified variable NAME. If
1 TIMEOUT is 0, 'read' returns immediately, without trying to
1 read and data. The exit status is 0 if input is available on
1 the specified file descriptor, non-zero otherwise. The exit
1 status is greater than 128 if the timeout is exceeded.
1
1 '-u FD'
1 Read input from file descriptor FD.
1
1 'readarray'
1 readarray [-d DELIM] [-n COUNT] [-O ORIGIN] [-s COUNT] [-t] [-u FD]
1 [-C CALLBACK] [-c QUANTUM] [ARRAY]
1
1 Read lines from the standard input into the indexed array variable
1 ARRAY, or from file descriptor FD if the '-u' option is supplied.
1
1 A synonym for 'mapfile'.
1
1 'source'
1 source FILENAME
1
1 A synonym for '.' (⇒Bourne Shell Builtins).
1
1 'type'
1 type [-afptP] [NAME ...]
1
1 For each NAME, indicate how it would be interpreted if used as a
1 command name.
1
1 If the '-t' option is used, 'type' prints a single word which is
1 one of 'alias', 'function', 'builtin', 'file' or 'keyword', if NAME
1 is an alias, shell function, shell builtin, disk file, or shell
1 reserved word, respectively. If the NAME is not found, then
1 nothing is printed, and 'type' returns a failure status.
1
1 If the '-p' option is used, 'type' either returns the name of the
1 disk file that would be executed, or nothing if '-t' would not
1 return 'file'.
1
1 The '-P' option forces a path search for each NAME, even if '-t'
1 would not return 'file'.
1
1 If a command is hashed, '-p' and '-P' print the hashed value, which
1 is not necessarily the file that appears first in '$PATH'.
1
1 If the '-a' option is used, 'type' returns all of the places that
1 contain an executable named FILE. This includes aliases and
1 functions, if and only if the '-p' option is not also used.
1
1 If the '-f' option is used, 'type' does not attempt to find shell
1 functions, as with the 'command' builtin.
1
1 The return status is zero if all of the NAMES are found, non-zero
1 if any are not found.
1
1 'typeset'
1 typeset [-afFgrxilnrtux] [-p] [NAME[=VALUE] ...]
1
1 The 'typeset' command is supplied for compatibility with the Korn
1 shell. It is a synonym for the 'declare' builtin command.
1
1 'ulimit'
1 ulimit [-HSabcdefiklmnpqrstuvxPT] [LIMIT]
1
1 'ulimit' provides control over the resources available to processes
1 started by the shell, on systems that allow such control. If an
1 option is given, it is interpreted as follows:
1
1 '-S'
1 Change and report the soft limit associated with a resource.
1
1 '-H'
1 Change and report the hard limit associated with a resource.
1
1 '-a'
1 All current limits are reported.
1
1 '-b'
1 The maximum socket buffer size.
1
1 '-c'
1 The maximum size of core files created.
1
1 '-d'
1 The maximum size of a process's data segment.
1
1 '-e'
1 The maximum scheduling priority ("nice").
1
1 '-f'
1 The maximum size of files written by the shell and its
1 children.
1
1 '-i'
1 The maximum number of pending signals.
1
1 '-k'
1 The maximum number of kqueues that may be allocated.
1
1 '-l'
1 The maximum size that may be locked into memory.
1
1 '-m'
1 The maximum resident set size (many systems do not honor this
1 limit).
1
1 '-n'
1 The maximum number of open file descriptors (most systems do
1 not allow this value to be set).
1
1 '-p'
1 The pipe buffer size.
1
1 '-q'
1 The maximum number of bytes in POSIX message queues.
1
1 '-r'
1 The maximum real-time scheduling priority.
1
1 '-s'
1 The maximum stack size.
1
1 '-t'
1 The maximum amount of cpu time in seconds.
1
1 '-u'
1 The maximum number of processes available to a single user.
1
1 '-v'
1 The maximum amount of virtual memory available to the shell,
1 and, on some systems, to its children.
1
1 '-x'
1 The maximum number of file locks.
1
1 '-P'
1 The maximum number of pseudoterminals.
1
1 '-T'
1 The maximum number of threads.
1
1 If LIMIT is given, and the '-a' option is not used, LIMIT is the
1 new value of the specified resource. The special LIMIT values
1 'hard', 'soft', and 'unlimited' stand for the current hard limit,
1 the current soft limit, and no limit, respectively. A hard limit
1 cannot be increased by a non-root user once it is set; a soft limit
1 may be increased up to the value of the hard limit. Otherwise, the
1 current value of the soft limit for the specified resource is
1 printed, unless the '-H' option is supplied. When setting new
1 limits, if neither '-H' nor '-S' is supplied, both the hard and
1 soft limits are set. If no option is given, then '-f' is assumed.
1 Values are in 1024-byte increments, except for '-t', which is in
1 seconds; '-p', which is in units of 512-byte blocks; '-P', '-T',
1 '-b', '-k', '-n' and '-u', which are unscaled values; and, when in
1 POSIX Mode (⇒Bash POSIX Mode), '-c' and '-f', which are in
1 512-byte increments.
1
1 The return status is zero unless an invalid option or argument is
1 supplied, or an error occurs while setting a new limit.
1
1 'unalias'
1 unalias [-a] [NAME ... ]
1
1 Remove each NAME from the list of aliases. If '-a' is supplied,
1 all aliases are removed. Aliases are described in ⇒Aliases.
1