zsh - Shell Builtin Commands

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# Shell Builtin Commands

`- simple command`
  See section Precommand Modifiers.
`. file [ arg ... ]`
  Read and execute commands from file and execute them in the current shell environment. If file does not contain a slash, or if `PATH_DIRS` is set, the shell looks in the components of `path` to find the directory containing file. Files in the current directory are not read unless ``.'` appears somewhere in `path`. If any arguments arg are given, they become the positional parameters; the old positional parameters are restored when the file is done executing. The exit status is the exit status of the last command executed.
`: [ arg ... ]`
  This command only expands parameters. A zero exit code is returned.
`alias [ -grmL ] [ name[=value] ] ...`
  For each name with a corresponding value, define an alias with that value. A trailing space in value causes the next word to be checked for alias substitution. If the ``-g'` flag is present, define a global alias; global aliases are expanded even if they do not occur in command position. For each name with no value, print the value of name, if any. With no arguments, print all currently defined aliases. If the ``-m'` flag is given the arguments are taken as patterns (they should be quoted to preserve them from being interpreted as glob patterns) and the aliases matching these patterns are printed. When printing aliases and the ``-g'` or ``-r'` flags are present, then restrict the printing to global or regular aliases, respectively. If the ``-L'` flag is present, then print each alias in a manner suitable for putting in a startup script. The exit status is nonzero if a name (with no value) is given for which no alias has been defined.
`autoload [ name ... ]`
  For each of the names (which are names of functions), create a function marked undefined. The `fpath` variable will be searched to find the actual function definition when the function is first referenced. The definition is contained in a file of the same name as the function. If the file found contains a standard definition for the function, that is stored as the function; otherwise, the contents of the entire file are stored as the function. The latter format allows functions to be used directly as scripts.
`bg [ job ... ]`
`job ... &`
  Put each specified job in the background, or the current job if none is specified. See section Jobs & Signals.
`bindkey -mevd`
`bindkey -r in-string ...`
`bindkey [ -a ] in-string [ command ] ...`
`bindkey -s [ -a ] in-string out-string ...`
  The ``-e'` and ``-v'` options put the keymaps in emacs mode and vi mode respectively; they cannot be used simultaneously. The ``-d'` option resets all bindings to the compiled-in settings. If not used with options ``-e'` or ``-v'`, the maps will be left in emacs mode, or in vi mode if the `VISUAL` or `EDITOR` variables contain the string ``vi'`. Metafied characters are bound to self-insert by default. The ``-m'` option loads the compiled-in bindings of these characters for the mode determined by the preceding options, or the current mode if used alone. Any previous binding done by the user will be preserved. If the ``-r'` option is given, remove any binding for each in-string. If the ``-s'` option is not specified, bind each in-string to a specified command. If no command is specified, print the binding of in-string if it is bound, or return a nonzero exit code if it is not bound. If the ``-s'` option is specified, bind each in-string to each specified out-string. When in-string is typed, out-string will be pushed back and treated as input to the line editor. The process is recursive, but to avoid infinite loops the shell will report an error if more than 20 consecutive replacements happen. If the ``-a'` option is specified, bind the in-strings in the alternative keymap instead of the standard one. The alternative keymap is used in vi command mode. It's possible for an in-string to be bound to something and also be the beginning of a longer bound string. In this case the shell will wait a certain time to see if more characters are typed, and if not it will execute the binding. This timeout is defined by the `KEYTIMEOUT` parameter; the default is 0.4 seconds. No timeout is done if the prefix string is not bound. For either in-string or out-string, control characters may be specified in the form `^X`, and the backslash may be used to introduce one of the following escape sequences:
  `\a`
    Bell character
  `\n`
    Linefeed (newline)
  `\b`
    Backspace
  `\t`
    Horizontal tab
  `\v`
    Vertical tab
  `\f`
    Form feed
  `\r`
    Carriage return
  `\e`
  `\E`
    Escape
  `\NNN`
    Character code in octal
  `\xNN`
    Character code in hexadecimal
  `\M-xxx`
    Character or escape sequence with meta bit set. The `-` after the `M` is optional.
  `\C-X`
    Control character. The ``-'` after the `M` is optional.
  In all other cases, `\` escapes the following character. Delete is written as `^?`. Note that `\M^?` and `^\M?` are not the same. Multi-character in-strings cannot contain the null character (`^@` or `^` ). If they appear in a bindkey command, they will be silently translated to `\M-^@`. This restriction does not apply to out-strings, single-character in-strings and the first character of a multi-char in-string.
`break [ n ]`
  Exit from an enclosing `for`, `while`, `until`, `select`, or `repeat` loop. If n is specified, then break n levels instead of just one.
`builtin name [ args ] ...`
  Executes the builtin name, with the given args.
`bye`
  Same as `exit`.
`cd [ arg ]`
`cd old new`
`cd [+-]n`
  Change the current directory. In the first form, change the current directory to arg, or to the value of `HOME` if arg is not specified. If arg is `-`, change to the value of `OLDPWD`, the previous directory. If a directory named arg is not found in the current directory and arg does not begin with a slash, search each component of the shell parameter `cdpath`. If the option `CDABLEVARS` is set, and a parameter named arg exists whose value begins with a slash, treat its value as the directory. The second form of `cd` substitutes the string new for the string old in the name of the current directory, and tries to change to this new directory. The third form of `cd` extracts an entry from the directory stack, and changes to that directory. An argument of the form `+n` identifies a stack entry by counting from the left of the list shown by the `dirs` command, starting with zero. An argument of the form `-n` counts from the right. If the `PUSHD_MINUS` option is set, the meanings of `+` and `-` in this context are swapped.
`chdir`
  Same as `cd`.
`command simple command`
  See section Precommand Modifiers.
`compctl`
  See section Programmable Completion.
`continue [ num ]`
  Resume the next iteration of the enclosing `for`, `while`, `until`, `select`, or `repeat` loop. If n is specified, break out of n-1 loops and resume at the n'th enclosing loop.
`declare [ arg ... ]`
  Same as `typeset`.
`dirs [ -v ] [ arg ... ]`
  With no arguments, print the contents of the directory stack. If the ``-v'` option is given, number the directories in the stack when printing. Directories are added to this stack with the `pushd` command, and removed with the `cd` or `popd` commands. If arguments are specified, load them onto the directory stack, replacing anything that was there, and push the current directory onto the stack.
`disable [ -afmr ] arg ...`
  Disable the hash table element named arg temporarily. The default is to disable builtin commands. This allows you to use an external command with the same name as a builtin command. The ``-a'` option causes `disable` to act on aliases. The ``-f'` option causes `disable` to act on shell functions. The ``-r'` option causes `disable` to act on reserved words. Without arguments all disabled hash table elements from the corresponding hash table are printed. With the ``-m'` flag the arguments are taken as patterns (which should be quoted to preserve them from being taken as glob patterns) and all hash table elements from the corresponding hash table matching these patterns are disabled. Disabled objects can be enabled with the `enable` command.
`disown [ job ... ]`
`job ... &|`
`job ... &!`
  Remove the specified jobs from the job table; the shell will no longer report their status, and will not complain if you try to exit an interactive shell with them running or stopped. If no `job` is specified use the current `job`.
`echo [ -neE ] [ arg ... ]`
  Write each arg on the standard output, with a space separating each one. If the ``-n'` flag is not present, print a newline at the end. `echo` recognizes the following escape sequences:
  `\a`
    Bell
  `\b`
    Backspace
  `\c`
    Don't print an ending newline
  `\e`
    Escape
  `\f`
    Form feed
  `\n`
    Newline
  `\r`
    Carriage return
  `\t`
    Horizontal tab
  `\v`
    Vertical tab
  `\\`
    Backslash
  `\0NNN`
    Character code in octal, with a maximum of three digits after the zero. A non-octal digit terminates the number.
  `\xNN`
    Character code in hexadecimal, with a maximum of two digits after the `x`. A non-hexadecimal digit terminates the number.
  The ``-E'` flag or the `BSD_ECHO` option can be used to disable these escape sequences. In the later case ``-e'` flag can be used to enable them.
`echotc cap [ arg ... ]`
  Output the termcap string corresponding to the capability cap, with optional arguments.
`emulate [ -R ] [ zsh | sh | ksh | csh ]`
  Set up zsh options to emulate the specified shell as much as possible. `csh` will never be fully emulated. If the argument is not one of the shells listed above, `zsh` will be used as a default. If the ``-R'` option is given, all options are reset to their default value corresponding to the specified emulation mode.
`enable [ -afmr ] arg ...`
  Enable the hash table element named arg, presumably disabled earlier with `disable`. The default is to enable builtin commands. The ``-a'` option causes `enable` to act on aliases. The ``-f'` option causes `enable` to act on shell functions. The ``-r'` option causes `enable` to act on reserved words. Without arguments all enable hash table elements from the corresponding hash table are printed. With the ``-m'` flag the arguments are taken as patterns (should be quoted) and all hash table elements from the corresponding hash table matching these patterns are enabled. Enabled objects can be disabled with the `disable` builtin command.
`eval [ arg ... ]`
  Read the arguments as input to the shell and execute the resulting command(s) in the current shell process.
`exec simple command`
  See section Precommand Modifiers.
`exit [ n ]`
  Exit the shell with the exit code specified by n; if none is specified, use the exit code from the last command executed. An `EOF` condition will also cause the shell to exit, unless the `IGNORE_EOF` option is set.
`export [ name[=value] ... ]`
  The specified names are marked for automatic export to the environment of subsequently executed commands. `export` is equivalent to `typeset -x`.
`false`
  Do nothing and return an exit code of 1.
`fc [ -e ename ] [ -nlrdDfEim ] [ old=new ... ] [ first [ last ]]`
`fc -ARWI [ filename ]`
  Select a range of commands from first to last from the history list. The arguments first and last may be specified as a number or as a string. A negative number is used as an offset to the current history event number. A string specifies the most recent event beginning with the given string. All substitutions old=new, if any, are then performed on the commands. If the ``-l'` flag is given, the resulting commands are listed on standard output. If the ``-m'` flag is also given the first argument is taken as a pattern (which should be quoted), and only the history events matching this pattern will be shown. Otherwise the editor program ename is invoked on a file containing these history events. If ename is not given, the value of the parameter `FCEDIT` is used. If ename is `-`, no editor is invoked. When editing is complete, the edited command(s) is executed. If first is not specified, it will be set to -1 (the most recent event), or to -16 if the ``-l'` flag is given. If last is not specified, it will be set to first, or to -1 if the ``-l'` flag is given. The flag ``-r'` reverses the order of the commands and the flag ``-n'` suppresses command numbers when listing. Also when listing, ``-d'` prints timestamps for each command, ``-f'` prints full time and date stamps. Adding the ``-E'` flag causes the dates to be printed as (`dd.mm.yyyy`), instead of the default, `mm/dd/yyyy`. Adding the ``-i'` flag causes the dates to be printed as `yyyy-mm-dd`, in a fixed format. With the ``-D'` flag, `fc` prints elapsed times. `fc -R` reads the history from the given file, `fc -W` writes the history out to the given file, and `fc -A` appends the history out to the given file. `fc -AI` (`WI`) appends (writes) only those events that are new since the last incremental append (write) to the history file. In any case the file will have no more than `SAVEHIST` entries.
`fg [ job ... ]`
`job ...`
  Bring the specified jobs to the foreground. If no job is specified, use the current job.
`functions [ +-tum ] [ name ... ]`
  Equivalent to `typeset -f`.
`getln name ...`
  Read the top value from the buffer stack and put it in the shell parameter name. Equivalent to `read -zr`. The flags ``-c'`, ``-l'`, ``-A'`, ``-e'`, ``-E'`, and ``-n'` are also supported.
`getopts optstring name [ arg ... ]`
  Checks arg for legal options. If arg is omitted, use the positional parameters. A valid option argument begins with a `+` or a `-`. An argument not beginning with a `+` or a `-`, or the argument `--`, ends the options. optstring contains the letters that `getopts` recognizes. If a letter is followed by a `:`, that option is expected to have an argument. The options can be separated from the argument by blanks. Each time it is invoked, `getopts` places the option letter it finds in the shell parameter name, prepended with a `+` when arg begins with a `+`. The index of the next arg is stored in `OPTIND`. The option argument, if any, is stored in `OPTARG`. A leading `:` in optstring causes `getopts` to store the letter of the invalid option in `OPTARG`, and to set name to `?` for an unknown option and to `:` when a required option is missing. Otherwise, `getopts` prints an error message. The exit status is nonzero when there are no more options.
`hash [ -dfmr ] [ name[=value ] ] ...`
  With no arguments or options, `hash` will list the entire command hash table. The ``-m'` option causes the arguments to be taken as patterns (they should be quoted) and the elements of the command hash table matching these patterns are printed. The ``-r'` option causes the command hash table to be thrown out and restarted. The ``-f'` option causes the entire path to be searched, and all the commands found are added to the hash table. These options cannot be used with any arguments. For each name with a corresponding value, put name in the command hash table, associating it with the pathname value. Whenever name is used as a command argument, the shell will try to execute the file given by value. For each name with no corresponding value, search for name in the path, and add it to the command hash table, and associating it with the discovered path, if it is found. Adding the ``-d'` option causes `hash` to act on the named directory table instead of the command hash table. The remaining discussion of `hash` will assume that the ``-d'` is given. If invoked without any arguments, and without any other options, `hash -d` lists the entire named directory table. The ``-m'` option causes the arguments to be taken as patterns (they should be quoted) and the elements of the named directory table matching these patterns are printed. The ``-r'` option causes the named directory table to be thrown out and restarted so that it only contains `~`. The ``-f'` option causes all usernames to be added to the named directory table. These options cannot be used with any arguments. For each name with a corresponding value, put name in the named directory table. The directory name name is then associated with the specified path value, so that value may be referred to as `~name`. For each name with no corresponding value, search for as a username and as a parameter. If it is found, it is added to the named directory hash table.
`history [ -nrdDfEim ] [ first [ last ]]`
  Same as `fc -l`.
`integer [ +-lrtux ] [ name[=value] ]`
  Same as `typeset -i`, except that options irrelevant to integers are not permitted.
`jobs [ -lprs ] [ job ... ]`
  Lists information about each given job, or all jobs if job is omitted. The ``-l'` flag lists process ids, and the ``-p'` flag lists process groups. If the ``-r'` flag is given only running jobs will be listed; if the ``-s'` flag is given only stopped jobs are shown.
`kill [ -s signal_name ] job ...`
`kill [ -sig ] job ...`
`kill -l [ sig ... ]`
  Sends either `SIGTERM` or the specified signal to the given jobs or processes. Signals are given by number or by names, without the `SIG` prefix. If the signal being sent is not `KILL` or `CONT`, then the job will be sent a `CONT` signal if it is stopped. The argument job can be the process id of a job not in the job list. In the third form, `kill -l`, if sig is not specified the signal names are listed. Otherwise, for each sig that is a name, the corresponding signal number is listed. For each sig that is a signal number or a number representing the exit status of a process which was terminated or stopped by a signal the name of the signal is printed.
`let arg ...`
  Evaluate each arg as an arithmetic expression. See section Arithmetic Evaluation, for a description of arithmetic expressions. The exit status is 0 if the value of the last expression is nonzero, and 1 otherwise.
`limit [ -hs ] [ resource [ limit ] ] ...`
  Set or display resource limits. Unless the ``-s'` flag is given the limit applies only the children of the shell. If ``-s'` is given without other arguments, the resource limits of the current shell is set to the previously set resource limits of the children. If limit is not specified, print the current limit placed on resource; otherwise set the limit to the specified value. If the ``-h'` flag is given, use hard limits instead of soft limits. If no resource is given, print all limits.
  resource is one of:
  `cputime`
    Maximum CPU seconds per process.
  `filesize`
    Largest single file allowed.
  `datasize`
    Maximum data size (including stack) for each process.
  `stacksize`
    Maximum stack size for each process.
  `coredumpsize`
    Maximum size of a core dump.
  `resident`
  `memoryuse`
    Maximum resident set size.
  `memorylocked`
    Maximum amount of memory locked in RAM.
  `descriptors`
    Maximum value for a file descriptor.
  `openfiles`
    Maximum number of open files.
  `vmemorysize`
    Maximum amount of virtual memory.
  Which of these resource limits are available depends on the system. limit is a number, with an optional scaling factor, as follows:
  `nh`
    Hours.
  `nk`
    Kilobytes. This is the default for all but cputime.
  `nm`
    Megabytes or minutes.
  `mm:ss`
    Minutes and seconds.
`local [ +-LRZilrtu [n]] [ name[=value] ]`
  Same as `typeset`, except that the options ``-x'` and ``-f'` are not permitted.
`log`
  List all users currently logged in who are affected by the current setting of the `watch` parameter.
`logout`
  Exit the shell, if this is a login shell.
`noglob simple command`
  See section Precommand Modifiers.
`popd [ +-n ]`
  Removes a entry from the directory stack and, performs a `cd` to the new top directory. With no argument, the current top entry is removed. An argument of the form `+n` identifies a stack entry by counting from the left of the list shown by the `dirs` command, starting with zero. An argument of the form ``-n'` counts from the right. If the `PUSHD_MINUS` option is set, the meanings of `+` and `-` in this context are swapped.
`print [ -nrslzpNDPoOicm ] [ -un ] [ -R [ -en ]] [ arg ... ]`
  With no flags or with flag `-`, the arguments are printed on the standard output as described by `echo`, with the following differences: the escape sequence `\M-x` metafies the character `x` (sets the highest bit), `\C-x` produces a control character (`\C-@` and `\C-?` give the characters NULL and delete) and `\E` is a synonym for `\e`. Finally, if not in an escape sequence, `\` escapes the following character and is not printed.
  `-r`
    Ignore the escape conventions of `echo`.
  `-R`
    Emulate the BSD `echo` command which does not process escape sequences unless the ``-e'` flag is given. The ``-n'` flag suppresses the trailing newline. Only the ``-e'` and ``-n'` flags are recognized after ``-R'`, all other arguments and options are printed.
  `-m`
    Take the fist argument as a pattern (should be quoted) and remove it from the argument list together with subsequent arguments that do not match this pattern.
  `-s`
    Place the results in the history list instead of on the standard output.
  `-n`
    Do not add a newline to the output.
  `-l`
    Print the arguments separated by newlines instead of spaces.
  `-N`
    Print the arguments separated and terminated by nulls.
  `-o`
    Print the arguments sorted in ascending order.
  `-O`
    Print the arguments sorted in descending order.
  `-i`
    If given together with ``-o'` or ``-O'`, makes the sort be case-insensitive.
  `-c`
    Print the arguments in columns.
  `-un`
    Print the arguments to file descriptor n.
  `-p`
    Print the arguments to the input of the coprocess.
  `-z`
    Push the arguments onto the editing buffer stack, separated by spaces; no escape sequences are recognized.
  `-D`
    Treat the arguments as directory names, replacing prefixes with `~` expressions, as appropriate.
  `-P`
    Recognize the same escape sequences as in the `PROMPT` parameter.
`pushd [ arg ]`
`pushd old new`
`pushd +-n`
  Change the current directory, and push the old current directory onto the directory stack. In the first form, change the current directory to arg. If arg is not specified, change to the second directory on the stack (that is, exchange the top two entries), or change to the value of `HOME` if the `PUSHD_TO_HOME` option is set or if there is only one entry on the stack. If arg is `-`, change to the value of `OLDPWD`, the previous directory. If a directory named arg is not found in the current directory and arg does not contain a slash, search each component of the shell parameter `cdpath`. If the option `CDABLEVARS` is set, and a parameter named arg exists whose value begins with a slash, treat its value as the directory. If the option `PUSHD_SILENT` is not set, the directory stack will be printed after a `pushd` is performed. The second form of `pushd` substitutes the string new for the string old in the name of the current directory, and tries to change to this new directory. The third form of `pushd` changes directory by rotating the directory list. An argument of the form `+n` identifies a stack entry by counting from the left of the list shown by the `dirs` command, starting with zero. An argument of the form ``-n'` counts from the right. If the `PUSHD_MINUS` option is set, the meanings of `+` and `-` in this context are swapped.
`pushln`
  Equivalent to `print -nz`.
`pwd [ -r ]`
  Print the absolute pathname of the current working directory. If the ``-r'` flag is specified or the `CHASE_LINKS` option is set, the printed path will not contain symbolic links.
`r`
  Equivalent to `fc -e -`.
`read [ -rzpqAclneE ] [ -k [num] ] [ -un ] [ name?prompt ] [ name ... ]`
  Read one line and break it into fields using the characters in `IFS` as separators.
  `-r`
    Raw mode: a `\` at the end of a line does not signify line continuation.
  `-q`
    Read only one character from the terminal and set name to ``y'` if this character was ``y'` or ``Y'` and to ``n'` otherwise. With this flag set the return value is zero only if the character was ``y'` or ``Y'`.
  `-k [ num ]`
    Read only one (or num) characters from the terminal.
  `-z`
    Read from the editor buffer stack. The first field is assigned to the first name, the second field to the second name, etc., with leftover fields assigned to the last name.
  `-e`
  `-E`
    The words read are printed after the whole line is read. If the ``-e'` flag is set, the words are not assigned to the parameters.
  `-A`
    The first name is taken as the name of an array and all words are assigned to it.
  `-c`
  `-l`
    These flags are allowed only if called inside a function used for completion (specified with the ``-K'` flag to `compctl`). If the ``-c'` flag is given, the words of the current command are read. If the ``-l'` flag is given, the whole line is assigned as a scalar. If `name` is omitted then `REPLY` is used for scalars and `reply` for arrays.
  `-n`
    Together with either of the previous flags, this option gives the number of the word the cursor is on or the index of the character the cursor is on respectively.
  `-un`
    Input is read from file descriptor n.
  `-p`
    Input is read from the coprocess.
  If the first argument contains a `?`, the remainder of this word is used as a `prompt` on standard error when the shell is interactive. The exit status is `0` unless an end-of-file is encountered.
`readonly [ name[=value]] ...`
  The given names are marked readonly; these names cannot be changed by subsequent assignment.
`rehash [ -df ]`
  Throw out the command hash table and start over. If the ``-f'` option is set, rescan the command path immediately, instead of rebuilding the hash table incrementally. The ``-d'` option causes `rehash` to act on the named directory table instead of the command hash table. This reduces the named directory table to only the `~` entry. If the ``-f'` option is also used, the named directory table is rebuilt immediately. `rehash` is equivalent to `hash -r`.
`return [ n ]`
  Causes a shell function or `.` script to return to the invoking script with the return status specified by n. If n is omitted then the return status is that of the last command executed. If `return` was executed from a trap in a ``TRAPxxx'` function, the effect is different for zero and nonzero return status. With zero status (or after an implicit return at the end of the trap), the shell will return to whatever it was previously processing; with a non-zero status, the shell will behave as interrupted except that the return status of the trap is retained. Note that the signal which caused the trap is passed as the first argument, so the statement ``return $((128+$1))'` will return the same status as if the signal had not been trapped.
`sched [+]hh:mm command ...`
`sched [ -item ]`
  Make an entry in the scheduled list of commands to execute. The time may be specified in either absolute or relative time. With no arguments, prints the list of scheduled commands. With the argument `-item`, removes the given item from the list.
`set [ +-options ] [ +-o option name ] ... [ +-A [ name ] ] [ arg ... ]`
  Set the options for the shell and/or set the positional parameters, or declare an array. If the ``-s'` option is given it causes the specified arguments to be sorted before assigning them to the positional parameters (or to the array name if ``-A'` is used). With ``+s'` sort arguments in descending order. See section Options, for the meaning of the other flags. Flags may be specified by name using the ``-o'` option. If the ``-A'` flag is specified, name is set to an array containing the given args; if ``+A'` is used and name is an array, the gien arguments will replace the initial elements of that array; if no name is specified, all arrays are printed. Otherwise the positional parameters are set. If no arguments are given, then the names and values of all parameters are printed on the standard output. If the only argument is `+`, the names of all parameters are printed.
`setopt [ -m ] [ +-options ] [ name ... ]`
  Set the options for the shell. All options specified either with flags or by name are set. If no arguments are supplied, the names of all options currently set are printed. In option names, case is insignificant, and all underscore characters are ignored. If the ``-m'` flag is given the arguments are taken as patterns (which should be quoted to preserve them from being interpreted as glob patterns), and all options with names matching these patterns are set.
`shift [ n ] [ name ... ]`
  The positional parameters from `$n+1` ... are renamed `$1`, where n is an arithmetic expression that defaults to 1. If any names are given then the arrays with these names are shifted, instead of the positional parameters.
`source`
  Same as ``.'`, except that the current directory is always searched and is always searched first, before directories in `path`.
`suspend [ -f ]`
  Suspend the execution of the shell (send it a `SIGTSTP`) until it receives a `SIGCONT`. If the ``-f'` option is not given, complain if this is a login shell.
`test arg ...`
`[ arg ... ]`
  Like the system version of `test`. Added for compatibility; use conditional expressions instead.
`times`
  Print the accumulated user and system times for the shell and for processes run from the shell.
`trap [ arg ] [ sig ] ...`
  arg is a command to be read and executed when the shell receives sig. Each sig can be given as a number or as the name of a signal. If arg is `-`, then all traps sig are reset to their default values. If arg is the null string, then this signal is ignored by the shell and by the commands it invokes. If sig is `ZERR` then arg will be executed after each command with a nonzero exit status. If sig is `DEBUG` then arg will be executed after each command. If sig is `0` or `EXIT` and the `trap` statement is executed inside the body of a function, then the command arg is executed after the function completes. If sig is `0` or `EXIT` and the `trap` statement is not executed inside the body of a function, then the command arg is executed when the shell terminates. The `trap` command with no arguments prints a list of commands associated with each signal.
`true`
  Do nothing and return an exit code of 0.
`ttyctl [ -fu ]`
  The ``-f'` option freezes the tty, and ``-u'` un-freezes it. When the tty is frozen, no changes made to the tty settings by external programs will be honoured by the shell, except for changes in the size of the screen; the shell will simply reset the settings to their previous values as soon as each command exits. Thus, `stty` and similar programs have no effect when the tty is frozen. Without options it reports whether the terminal is frozen or not.
`type [ -fpam ] name ...`
  Same as `whence -v`.
`typeset [ +-LRUZfilrtuxm [n]] [ name[=value]] ...`
  Set attributes and values for shell parameters. When invoked inside a function, a new parameter is created which will be unset when the function completes. The new parameter will not be exported unless `ALL_EXPORT` is set, in which case the parameter will be exported provided no parameter of that name already exists. The following attributes are valid:
  `-L`
    Left justify and remove leading blanks from value. If n is nonzero, it defines the width of the field; otherwise it is determined by the width of the value of the first assignment. When the parameter is printed, it is filled on the right with blanks or truncated if necessary to fit the field. Leading zeros are removed if the ``-Z'` flag is also set.
  `-R`
    Right justify and fill with leading blanks. If n is nonzero it defines the width of the field; otherwise it is determined by the width of the value of the first assignment. When the parameter is printed, the field is left filled with blanks or truncated from the end.
  `-U`
    For arrays keep only the first element of each duplications. It can also be set for colon separated special parameters like `PATH` or `FIGNORE`, etc.
  `-Z`
    Right justify and fill with leading zeros if the first non-blank character is a digit and the ``-L'` flag has not been set. If n is nonzero it defines the width of the field; otherwise it is determined by the width of the value of the first assignment.
  `-f`
    The names refer to functions rather than parameters. No assignments can be made, and the only other valid flags are ``-t'` and ``-u'`. The flag ``-t'` turns on execution tracing for this function. The flag ``-u'` causes this function to be marked for autoloading. The `fpath` parameter will be searched to find the function definition when the function is first referenced.; see `autoload`.
  `-i`
    Use an internal integer representation. If n is nonzero it defines the output arithmetic base, otherwise it is determined by the first assignment.
  `-l`
    Convert to lower case.
  `-r`
    The given names are marked read-only.
  `-t`
    Tags the named parameters. Tags have no special meaning to the shell.
  `-u`
    Convert to upper case.
  `-x`
    Mark for automatic export to the environment of subsequently executed commands.
  Using `+` rather than `-` causes these flags to be turned off. If no arguments are given but flags are specified, a list of named parameters which have these flags set is printed. Using `+` instead of `-` keeps their values from being printed. If no arguments or options are given, the names and attributes of all parameters are printed. If only the ``-m'` flag is given the arguments are taken as patterns (which should be quoted), and all parameters or functions (with the ``-f'` flag) with matching names are printed.
`ulimit [ -SHacdflmnpstv ] [ limit ] ...`
  Set or display resource limits of the shell and the processes started by the shell. The value of limit can be a number in the unit specified below or the value `unlimited`. If the ``-H'` flag is given use hard limits instead of soft limits. If the ``-S'` flag is given together with the ``-H'` flag set both hard and soft limits. If no options are used, the file size limit (``-f'`) is assumed. If limit is omitted the current value of the specified resources are printed. When more than one resource values are printed the limit name and unit is printed before each value.
  `-a`
    Lists all of the current resource limits.
  `-c`
    Maximum size of core dumps, in 512-byte blocks.
  `-d`
    Maximum size of the data segment, in Kbytes.
  `-f`
    Maximum size of individual files written, in 512-byte blocks.
  `-l`
    Maximum size of locked-in memory, in Kbytes.
  `-m`
    Maximum size of physical memory, in Kbytes.
  `-n`
    Maximum number of open file descriptors.
  `-s`
    Maximum size of stack, in Kbytes.
  `-t`
    Maximum number of CPU seconds.
  `-u`
    The number of processes available to the user.
  `-v`
    Maximum size of virtual memory, in Kbytes.
`umask [ -S] [ mask ]`
  The umask is set to mask. mask can be either an octal number or a symbolic value as described in `chmod(1)`. If mask is omitted, the current value is printed. The ``-S'` option causes the mask to be printed as a symbolic value. Otherwise, the mask is printed as an octal number. Note that in the symbolic form the permissions you specify are those which are to be allowed (not denied) to the users specified).
`unalias [ -m ] name ...`
  The alias definition, if any, for each name is removed. With the ``-m'` flag, the arguments are taken as patterns (which should be quoted), and all aliases with matching names are removed. `unalias` is equivalent to `unhash -a`.
`unfunction [ -m ] name ...`
  The function definition, if any, for each name is removed. With the ``-m'` flag, the arguments are taken as patterns (which should be quoted), and all function with matching names are removed. `unfunction` is equivalent to `unhash -f`.
`unhash [ -adfm ] name ...`
  Remove the element named name from an internal hash table. The default is remove elements from the command hash table. The ``-a'` option causes `unhash` to remove aliases. The ``-f'` option causes `unhash` to remove shell functions. The ``-d'` options causes `unhash` to remove named directories. If the ``-m'` flag is given the arguments are taken as patterns (should be quoted) and all elements of the corresponding hash table with matching names will be removed.
`unlimit [ -hs ] resource ...`
  The resource limit for each resource is set to the hard limit. If the ``-h'` flag is given and the shell is running as root, the hard resource limit for each resource is removed. The resources of the shell process are only changed if the ``-s'` flag is given.
`unset [ -fm ] name ...`
  Each named parameter is unset. If the ``-m'` flag is set, the arguments are taken as patterns (which should be quoted), and all parameters with matching names are unset. `Unset -f` is equivalent to `unfunction`.
`unsetopt [ -m ] [ +-options ] [ name ... ]`
  Unset the options for the shell. All options specified either with flags or by name are unset. If the ``-m'` flag is given, the arguments are taken as patterns (which should be quoted), and all options with names matching these patterns are unset.
`vared [ -c ] [ -h ] [ -p prompt] [ -r rprompt ] name`
  The value of the parameter name is loaded into the edit buffer, and the line editor is invoked. When the editor exits, name is set to the string value returned by the editor. If the ``-c'` flag is given, the parameter is created if it doesn't already exist. If the ``-p'` flag is given, prompt will be taken as the prompt to display at the left and if the ``-r'` flag is given, the following string gives the prompt to display at the right. If the ``-h'` flag is specified, the history can be accessed from `zle`.
`wait [ job ... ]`
  Wait for the specified jobs or processes. If job is not given then all currently active child processes are waited for. Each job can be either a job specification or the process-id of a job in the job table. The exit status from this command is that of the job waited for.
`whence [ -vcfpam ] name ...`
  For each name, indicate how it would be interpreted if used as a command name. The ``-v'` flag produces a more verbose report. The ``-c'` flag prints the results in a csh-like format and takes precedence over ``-v'`. The ``-f'` flag causes the contents of a shell function to be displayed, which would otherwise not happen unless the ``-c'` flag were used. The ``-p'` flag does a path search for name even if it is an alias, reserved word, shell function or builtin. The ``-a'` flag does a search for all occurrences of name throughout the command path. With the ``-m'` flag, the arguments are taken as patterns (which should be quoted), and the information is displayed for each command matching one of these patterns.
`where`
  Same as `whence -ca`.
`which [ -pam ] name ...`
  Same as `whence -c`.

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