Translations by Marc Deslauriers

Unset values and attributes of shell variables and functions. For each NAME, remove the corresponding variable or function. Options: -f treat each NAME as a shell function -v treat each NAME as a shell variable -n treat each NAME as a name reference and unset the variable itself rather than the variable it references Without options, unset first tries to unset a variable, and if that fails, tries to unset a function. Some variables cannot be unset; also see `readonly'. Exit Status: Returns success unless an invalid option is given or a NAME is read-only.

Mark shell variables as unchangeable. Mark each NAME as read-only; the values of these NAMEs may not be changed by subsequent assignment. If VALUE is supplied, assign VALUE before marking as read-only. Options: -a refer to indexed array variables -A refer to associative array variables -f refer to shell functions -p display a list of all readonly variables or functions, depending on whether or not the -f option is given An argument of `--' disables further option processing. Exit Status: Returns success unless an invalid option is given or NAME is invalid.

Evaluate conditional expression. Exits with a status of 0 (true) or 1 (false) depending on the evaluation of EXPR. Expressions may be unary or binary. Unary expressions are often used to examine the status of a file. There are string operators and numeric comparison operators as well. The behavior of test depends on the number of arguments. Read the bash manual page for the complete specification. File operators: -a FILE True if file exists. -b FILE True if file is block special. -c FILE True if file is character special. -d FILE True if file is a directory. -e FILE True if file exists. -f FILE True if file exists and is a regular file. -g FILE True if file is set-group-id. -h FILE True if file is a symbolic link. -L FILE True if file is a symbolic link. -k FILE True if file has its `sticky' bit set. -p FILE True if file is a named pipe. -r FILE True if file is readable by you. -s FILE True if file exists and is not empty. -S FILE True if file is a socket. -t FD True if FD is opened on a terminal. -u FILE True if the file is set-user-id. -w FILE True if the file is writable by you. -x FILE True if the file is executable by you. -O FILE True if the file is effectively owned by you. -G FILE True if the file is effectively owned by your group. -N FILE True if the file has been modified since it was last read. FILE1 -nt FILE2 True if file1 is newer than file2 (according to modification date). FILE1 -ot FILE2 True if file1 is older than file2. FILE1 -ef FILE2 True if file1 is a hard link to file2. String operators: -z STRING True if string is empty. -n STRING STRING True if string is not empty. STRING1 = STRING2 True if the strings are equal. STRING1 != STRING2 True if the strings are not equal. STRING1 < STRING2 True if STRING1 sorts before STRING2 lexicographically. STRING1 > STRING2 True if STRING1 sorts after STRING2 lexicographically. Other operators: -o OPTION True if the shell option OPTION is enabled. -v VAR True if the shell variable VAR is set. -R VAR True if the shell variable VAR is set and is a name reference. ! EXPR True if expr is false. EXPR1 -a EXPR2 True if both expr1 AND expr2 are true. EXPR1 -o EXPR2 True if either expr1 OR expr2 is true. arg1 OP arg2 Arithmetic tests. OP is one of -eq, -ne, -lt, -le, -gt, or -ge. Arithmetic binary operators return true if ARG1 is equal, not-equal, less-than, less-than-or-equal, greater-than, or greater-than-or-equal than ARG2. Exit Status: Returns success if EXPR evaluates to true; fails if EXPR evaluates to false or an invalid argument is given.

Display information about command type. For each NAME, indicate how it would be interpreted if used as a command name. Options: -a display all locations containing an executable named NAME; includes aliases, builtins, and functions, if and only if the `-p' option is not also used -f suppress shell function lookup -P force a PATH search for each NAME, even if it is an alias, builtin, or function, and returns the name of the disk file that would be executed -p returns either the name of the disk file that would be executed, or nothing if `type -t NAME' would not return `file' -t output a single word which is one of `alias', `keyword', `function', `builtin', `file' or `', if NAME is an alias, shell reserved word, shell function, shell builtin, disk file, or not found, respectively Arguments: NAME Command name to be interpreted. Exit Status: Returns success if all of the NAMEs are found; fails if any are not found.

Modify shell resource limits. Provides control over the resources available to the shell and processes it creates, on systems that allow such control. Options: -S use the `soft' resource limit -H use the `hard' resource limit -a all current limits are reported -b the socket buffer size -c the maximum size of core files created -d the maximum size of a process's data segment -e the maximum scheduling priority (`nice') -f the maximum size of files written by the shell and its children -i the maximum number of pending signals -k the maximum number of kqueues allocated for this process -l the maximum size a process may lock into memory -m the maximum resident set size -n the maximum number of open file descriptors -p the pipe buffer size -q the maximum number of bytes in POSIX message queues -r the maximum real-time scheduling priority -s the maximum stack size -t the maximum amount of cpu time in seconds -u the maximum number of user processes -v the size of virtual memory -x the maximum number of file locks -P the maximum number of pseudoterminals -T the maximum number of threads Not all options are available on all platforms. If LIMIT is given, it is the new value of the specified resource; the special LIMIT values `soft', `hard', and `unlimited' stand for the current soft limit, the current hard limit, and no limit, respectively. Otherwise, the current value of the specified resource is printed. If no option is given, then -f is assumed. Values are in 1024-byte increments, except for -t, which is in seconds, -p, which is in increments of 512 bytes, and -u, which is an unscaled number of processes. Exit Status: Returns success unless an invalid option is supplied or an error occurs.

Create a coprocess named NAME. Execute COMMAND asynchronously, with the standard output and standard input of the command connected via a pipe to file descriptors assigned to indices 0 and 1 of an array variable NAME in the executing shell. The default NAME is "COPROC". Exit Status: The coproc command returns an exit status of 0.

Add directories to stack. 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. Options: -n Suppresses the normal change of directory when adding directories to the stack, so only the stack is manipulated. Arguments: +N Rotates the stack so that the Nth directory (counting from the left of the list shown by `dirs', 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 `dirs', starting with zero) is at the top. dir Adds DIR to the directory stack at the top, making it the new current working directory. The `dirs' builtin displays the directory stack. Exit Status: Returns success unless an invalid argument is supplied or the directory change fails.

Remove directories from stack. Removes entries from the directory stack. With no arguments, removes the top directory from the stack, and changes to the new top directory. Options: -n Suppresses the normal change of directory when removing directories from the stack, so only the stack is manipulated. Arguments: +N Removes the Nth entry counting from the left of the list shown by `dirs', 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 `dirs', starting with zero. For example: `popd -0' removes the last directory, `popd -1' the next to last. The `dirs' builtin displays the directory stack. Exit Status: Returns success unless an invalid argument is supplied or the directory change fails.

Display directory stack. Display the list of currently remembered directories. Directories find their way onto the list with the `pushd' command; you can get back up through the list with the `popd' command. Options: -c clear the directory stack by deleting all of the elements -l do not print tilde-prefixed versions of directories relative to your home directory -p print the directory stack with one entry per line -v print the directory stack with one entry per line prefixed with its position in the stack Arguments: +N Displays the Nth entry counting from the left of the list shown by dirs when invoked without options, starting with zero. -N Displays the Nth entry counting from the right of the list shown by dirs when invoked without options, starting with zero. Exit Status: Returns success unless an invalid option is supplied or an error occurs.

Formats and prints ARGUMENTS under control of the FORMAT. Options: -v var assign the output to shell variable VAR rather than display it on the standard output FORMAT 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 format specifications, each of which causes printing of the next successive argument. In addition to the standard format specifications described in printf(1), printf interprets: %b expand backslash escape sequences in the corresponding argument %q quote the argument in a way that can be reused as shell input %(fmt)T output the date-time string resulting from using FMT as a format string for strftime(3) The format is re-used as necessary to consume all of the arguments. If there are fewer arguments than the format requires, extra format specifications behave as if a zero value or null string, as appropriate, had been supplied. Exit Status: Returns success unless an invalid option is given or a write or assignment error occurs.

Specify how arguments are to be completed by Readline. For each NAME, specify how arguments are to be completed. If no options are supplied, existing completion specifications are printed in a way that allows them to be reused as input. Options: -p print existing completion specifications in a reusable format -r remove a completion specification for each NAME, or, if no NAMEs are supplied, all completion specifications -D apply the completions and actions as the default for commands without any specific completion defined -E apply the completions and actions to "empty" commands -- completion attempted on a blank line When completion is attempted, the actions are applied in the order the uppercase-letter options are listed above. The -D option takes precedence over -E. Exit Status: Returns success unless an invalid option is supplied or an error occurs.

Read lines from the standard input into an indexed array variable. Read lines from the standard input into the indexed array variable ARRAY, or from file descriptor FD if the -u option is supplied. The variable MAPFILE is the default ARRAY. Options: -d delim Use DELIM to terminate lines, instead of newline -n count Copy at most COUNT lines. If COUNT is 0, all lines are copied -O origin Begin assigning to ARRAY at index ORIGIN. The default index is 0 -s count Discard the first COUNT lines read -t Remove a trailing DELIM from each line read (default newline) -u fd Read lines from file descriptor FD instead of the standard input -C callback Evaluate CALLBACK each time QUANTUM lines are read -c quantum Specify the number of lines read between each call to CALLBACK Arguments: ARRAY Array variable name to use for file data If -C is supplied without -c, the default quantum is 5000. When CALLBACK is evaluated, it is supplied the index of the next array element to be assigned and the line to be assigned to that element as additional arguments. If not supplied with an explicit origin, mapfile will clear ARRAY before assigning to it. Exit Status: Returns success unless an invalid option is given or ARRAY is readonly or not an indexed array.