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zshbuiltins - zsh built-in commands
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 a file named `file.zwc' is found, is newer than file, and is the compiled form (created with the zcompile builtin) of file, then commands are read from that file instead of file.
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.
If the -s flags is present, define a suffix alias: if the command word on a command line is in the form `text.name', where text is any non-empty string, it is replaced by the text `value text.name'. Note that name is treated as a literal string, not a pattern. A trailing space in value is not special in this case. For example,
alias -s ps=gv
will cause the command `*.ps' to be expanded to `gv *.ps'. As alias expansion is carried out earlier than globbing, the `*.ps' will then be expanded. Suffix aliases constitute a different name space from other aliases (so in the above example it is still possible to create an alias for the command ps) and the two sets are never listed together.
For each name with no value, print the value of name, if any. With no arguments, print all currently defined aliases other than suffix 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 one of the -g, -r or -s flags is present, restrict the printing to global, regular or suffix aliases, respectively; a regular alias is one which is neither a global nor a suffix alias. Using `+' instead of `-', or ending the option list with a single `+', prevents the values of the aliases from being printed.
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.
The flag -X may be used only inside a shell function, and may not be followed by a name. It causes the calling function to be marked for autoloading and then immediately loaded and executed, with the current array of positional parameters as arguments. This replaces the previous definition of the function. If no function definition is found, an error is printed and the function remains undefined and marked for autoloading.
The flag +X attempts to load each name as an autoloaded function, but does not execute it. The exit status is zero (success) if the function was not previously defined and a definition for it was found. This does not replace any existing definition of the function. The exit status is nonzero (failure) if the function was already defined or when no definition was found. In the latter case the function remains undefined and marked for autoloading. If ksh-style autoloading is enabled, the function created will contain the contents of the file plus a call to the function itself appended to it, thus giving normal ksh autoloading behaviour on the first call to the function.
With the -w flag, the names are taken as names of files compiled with the zcompile builtin, and all functions defined in them are marked for autoloading.
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.
If the -s option is specified, cd refuses to change the current directory if the given pathname contains symlinks. If the -P option is given or the CHASE_LINKS option is set, symbolic links are resolved to their true values. If the -L option is given symbolic links are followed regardless of the state of the CHASE_LINKS option.
See also the section `Precommand Modifiers'.
If the jobs are currently stopped and the AUTO_CONTINUE option is not set, a warning is printed containing information about how to make them running after they have been disowned. If one of the latter two forms is used, the jobs will automatically be made running, independent of the setting of the AUTO_CONTINUE option.
The -E flag, or the BSD_ECHO option, can be used to disable these escape sequences. In the latter case, -e flag can be used to enable them.
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 (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 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, and -f prints full time-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 in ISO8601 `yyyy-mm-dd' format. With the -D flag, fc prints elapsed times.
`fc -p' pushes the current history list onto a stack and switches to a new history list. If the -a option is also specified, this history list will be automatically popped when the current function scope is exited, which is a much better solution than creating a trap function to call `fc -P' manually. If no arguments are specified, the history list is left empty, $HISTFILE is unset, and $HISTSIZE & $SAVEHIST are set to their default values. If one argument is given, $HISTFILE is set to that filename, $HISTSIZE & $SAVEHIST are left unchanged, and the history file is read in (if it exists) to initialize the new list. If a second argument is specified, $HISTSIZE & $SAVEHIST are instead set to the single specified numeric value. Finally, if a third argument is specified, $SAVEHIST is set to a separate value from $HISTSIZE. You are free to change these environment values for the new history list however you desire in order to manipulate the new history list.
`fc -P' pops the history list back to an older list saved by `fc -p'. The current list is saved to its $HISTFILE before it is destroyed (assuming that $HISTFILE and $SAVEHIST are set appropriately, of course). The values of $HISTFILE, $HISTSIZE, and $SAVEHIST are restored to the values they had when `fc -p' was called. Note that this restoration can conflict with making these variables "local", so your best bet is to avoid local declarations for these variables in functions that use `fc -p'. The one other guaranteed-safe combination is declaring these variables to be local at the top of your function and using the automatic option (-a) with `fc -p'. Finally, note that it is legal to manually pop a push marked for automatic popping if you need to do so before the function exits.
`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. If no filename is specified, the $HISTFILE is assumed. If the -I option is added to -R, only those events that are not already contained within the internal history list are added. If the -I option is added to -A or -W, only those events that are new since last incremental append/write to the history file are appended/written. In any case, the created file will have no more than $SAVEHIST entries.
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.
The first option to be examined may be changed by explicitly assigning to OPTIND. OPTIND has an initial value of 1, and is normally reset to 1 upon exit from a shell function. OPTARG is not reset and retains its value from the most recent call to getopts. If either of OPTIND or OPTARG is explicitly unset, it remains unset, and the index or option argument is not stored. The option itself is still stored in name in this case.
A leading `:' in optstring causes getopts to store the letter of any invalid option in OPTARG, and to set name to `?' for an unknown option and to `:' when a required option is missing. Otherwise, getopts sets name to `?' and prints an error message when an option is invalid. The exit status is nonzero when there are no more options.
Given no arguments, and neither the -r or -f options, the selected hash table will be listed in full.
The -r option causes the selected hash table to be emptied. It will be subsequently rebuilt in the normal fashion. The -f option causes the selected hash table to be fully rebuilt immediately. For the command hash table this hashes all the absolute directories in the PATH, and for the named directory hash table this adds all users' home directories. These two options cannot be used with any arguments.
The -m option causes the arguments to be taken as patterns (which should be quoted) and the elements of the hash table matching those patterns are printed. This is the only way to display a limited selection of hash table elements.
For each name with a corresponding value, put `name' in the selected hash table, associating it with the pathname `value'. In the command hash table, this means that whenever `name' is used as a command argument, the shell will try to execute the file given by `value'. In the named directory hash table, this means that `value' may be referred to as `~name'.
For each name with no corresponding value, attempt to add name to the hash table, checking what the appropriate value is in the normal manner for that hash table. If an appropriate value can't be found, then the hash table will be unchanged.
The -v option causes hash table entries to be listed as they are added by explicit specification. If has no effect if used with -f.
If the -L flag is present, then each hash table entry is printed in the form of a call to hash.
The -Z option replaces the shell's argument and environment space with the given string, truncated if necessary to fit. This will normally be visible in ps (ps(1)) listings. This feature is typically used by daemons, to indicate their state.
On some systems, alternative signal names are allowed for a few signals. Typical examples are SIGCHLD and SIGCLD or SIGPOLL and SIGIO, assuming they correspond to the same signal number. kill -l will only list the preferred form, however kill -l alt will show if the alternative form corresponds to a signal number. For example, under Linux kill -l IO and kill -l POLL both output 29, hence kill -IO and kill -POLL have the same effect.
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.
When looping over multiple resources, the shell will abort immediately if it detects a badly formed argument. However, if it fails to set a limit for some other reason it will continue trying to set the remaining limits.
resource can be one of:
Which of these resource limits are available depends on the system. resource can be abbreviated to any unambiguous prefix. It can also be an integer, which corresponds to the integer defined for the resource by the operating system.
If argument corresponds to a number which is out of the range of the resources configured into the shell, the shell will try to read or write the limit anyway, and will report an error if this fails. As the shell does not store such resources internally, an attempt to set the limit will fail unless the -s option is present.
limit is a number, with an optional scaling factor, as follows:
If any of `-m', `-o' or `-O' are used in combination with `-f' and there are no arguments (after the removal process in the case of `-m') then nothing is printed.
Normally, conversion specifications are applied to each argument in order but they can explicitly specify the nth argument is to be used by replacing `%' by `%n$' and `*' by `*n$'. It is recommended that you do not mix references of this explicit style with the normal style and the handling of such mixed styles may be subject to future change.
If arguments remain unused after formatting, the format string is reused until all arguments have been consumed. With the print builtin, this can be suppressed by using the -r option. If more arguments are required by the format than have been specified, the behaviour is as if zero or an empty string had been specified as the argument.
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.
If the option PUSHD_SILENT is not set, the directory stack will be printed after a pushd is performed.
The options -s, -L and -P have the same meanings as for the cd builtin.
The value (exit status) of read is 1 when an end-of-file is encountered, or when -c or -l is present and the command is not called from a compctl function, or as described for -q. Otherwise the value is 0.
The behavior of some combinations of the -k, -p, -q, -u and -z flags is undefined. Presently -q cancels all the others, -p cancels -u, -k cancels -z, and otherwise -z cancels both -p and -u.
The -c or -l flags cancel any and all of -kpquz.
If return was executed from a trap in a TRAPNAL function, the effect is different for zero and non-zero 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 numeric value of 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.
If the -A flag is specified, name is set to an array containing the given args; if no name is specified, all arrays are printed together with their values.
If +A is used and name is an array, the given arguments will replace the initial elements of that array; if no name is specified, all arrays are printed without their values.
The behaviour of arguments after -A name or +A name depends on whether the option KSH_ARRAYS is set. If it is not set, all arguments following name are treated as values for the array, regardless of their form. If the option is set, normal option processing continues at that point; only regular arguments are treated as values for the array. This means that
set -A array -x -- foo
sets array to `-x -- foo' if KSH_ARRAYS is not set, but sets the array to foo and turns on the option `-x' if it is set.
If the -A flag is not present, but there are arguments beyond the options, the positional parameters are set. If the option list (if any) is terminated by `--', and there are no further arguments, the positional parameters will be unset.
If no arguments and no `--' 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.
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.
ZERR, DEBUG and EXIT traps are not executed inside other traps.
The trap command with no arguments prints a list of commands associated with each signal.
Note that traps defined with the trap builtin are slightly different from those defined as `TRAPNAL () { ... }', as the latter have their own function environment (line numbers, local variables, etc.) while the former use the environment of the command in which they were called. For example,
trap 'print $LINENO' DEBUG
will print the line number of a command executed after it has run, while
TRAPDEBUG() { print $LINENO; }
will always print the number zero.
Alternative signal names are allowed as described under kill above. Defining a trap under either name causes any trap under an alternative name to be removed. However, it is recommended that for consistency users stick exclusively to one name or another.
A parameter is created for each name that does not already refer to one. When inside a function, a new parameter is created for every name (even those that already exist), and is unset again when the function completes. See `Local Parameters' in zshparam(1). The same rules apply to special shell parameters, which retain their special attributes when made local.
For each name=value assignment, the parameter name is set to value. Note that arrays currently cannot be assigned in typeset expressions, only scalars and integers.
If the shell option TYPESET_SILENT is not set, for each remaining name that refers to a parameter that is set, the name and value of the parameter are printed in the form of an assignment. Nothing is printed for newly-created parameters, or when any attribute flags listed below are given along with the name. Using `+' instead of minus to introduce an attribute turns it off.
If the -p option is given, parameters and values are printed in the form of a typeset comand and an assignment (which will be printed separately for arrays and associative arrays), regardless of other flags and options. Note that the -h flag on parameters is respected; no value will be shown for these parameters.
If the -T option is given, two or three arguments must be present (an exception is that zero arguments are allowed to show the list of parameters created in this fashion). The first two are the name of a scalar and an array parameter (in that order) that will be tied together in the manner of $PATH and $path. The optional third argument is a single-character separator which will be used to join the elements of the array to form the scalar; if absent, a colon is used, as with $PATH. Only the first character of the separator is significant; any remaining characters are ignored. Only the scalar parameter may be assigned an initial value. Both the scalar and the array may otherwise be manipulated as normal. If one is unset, the other will automatically be unset too. There is no way of untying the variables without unsetting them, or converting the type of one of them with another typeset command; +T does not work, assigning an array to SCALAR is an error, and assigning a scalar to array sets it to be a single-element array. Note that both `typeset -xT ...' and `export -T ...' work, but only the scalar will be marked for export. Setting the value using the scalar version causes a split on all separators (which cannot be quoted).
The -g (global) flag is treated specially: it means that any resulting parameter will not be restricted to local scope. Note that this does not necessarily mean that the parameter will be global, as the flag will apply to any existing parameter (even if unset) from an enclosing function. This flag does not affect the parameter after creation, hence it has no effect when listing existing parameters, nor does the flag +g have any effect except in combination with -m (see below).
If no name is present, the names and values of all parameters are printed. In this case the attribute flags restrict the display to only those parameters that have the specified attributes, and using `+' rather than `-' to introduce the flag suppresses printing of the values of parameters when there is no parameter name. Also, if the last option is the word `+', then names are printed but values are not.
If the -m flag is given the name arguments are taken as patterns (which should be quoted). With no attribute flags, all parameters (or functions with the -f flag) with matching names are printed (the shell option TYPESET_SILENT is not used in this case). Note that -m is ignored if no patterns are given. If the +g flag is combined with -m, a new local parameter is created for every matching parameter that is not already local. Otherwise -m applies all other flags or assignments to the existing parameters. Except when assignments are made with name=value, using +m forces the matching parameters to be printed, even inside a function.
If no attribute flags are given and either no -m flag is present or the +m form was used, each parameter name printed is preceded by a list of the attributes of that parameter (array, association, exported, integer, readonly). If +m is used with attribute flags, and all those flags are introduced with +, the matching parameter names are printed but their values are not.
The following attribute flags may be specified:
When looping over multiple resources, the shell will abort immediately if it detects a badly formed argument. However, if it fails to set a limit for some other reson it will continue trying to set the remaining limits.
A resource may also be specified by integer in the form `-N resource', where resource corresponds to the integer defined for the resource by the operating system. This may be used to set the limits for resources known to the shell which do not correspond to option letters. Such limits will be shown by number in the output of `ulimit -a'.
The number may alternatively be out of the range of limits compiled into the shell. The shell will try to read or write the limit anyway, and will report an error if this fails.
Individual elements of associative array parameters may be unset by using subscript syntax on name, which should be quoted (or the entire command prefixed with noglob) to protect the subscript from filename generation.
If the -m flag is specified the arguments are taken as patterns (should be quoted) and all parameters with matching names are unset. Note that this cannot be used when unsetting associative array elements, as the subscript will be treated as part of the pattern.
The -v flag specifies that name refers to parameters. This is the default behaviour.
unset -f is equivalent to unfunction.
The first form (without the -c, -a or -t options) creates a compiled file. If only the file argument is given, the output file has the name `file.zwc' and will be placed in the same directory as the file. The shell will load the compiled file instead of the normal function file when the function is autoloaded; see the section `Autoloading Functions' in zshfunc(1) for a description of how autoloaded functions are searched. The extension .zwc stands for `zsh word code'.
If there is at least one name argument, all the named files are compiled into the output file given as the first argument. If file does not end in .zwc, this extension is automatically appended. Files containing multiple compiled functions are called `digest' files, and are intended to be used as elements of the FPATH/fpath special array.
The second form, with the -c or -a options, writes the compiled definitions for all the named functions into file. For -c, the names must be functions currently defined in the shell, not those marked for autoloading. Undefined functions that are marked for autoloading may be written by using the -a option, in which case the fpath is searched and the contents of the definition files for those functions, if found, are compiled into file. If both -c and -a are given, names of both defined functions and functions marked for autoloading may be given. In either case, the functions in files written with the -c or -a option will be autoloaded as if the KSH_AUTOLOAD option were unset.
The reason for handling loaded and not-yet-loaded functions with different options is that some definition files for autoloading define multiple functions, including the function with the same name as the file, and, at the end, call that function. In such cases the output of `zcompile -c' does not include the additional functions defined in the file, and any other initialization code in the file is lost. Using `zcompile -a' captures all this extra information.
If the -m option is combined with -c or -a, the names are used as patterns and all functions whose names match one of these patterns will be written. If no name is given, the definitions of all functions currently defined or marked as autoloaded will be written.
The third form, with the -t option, examines an existing compiled file. Without further arguments, the names of the original files compiled into it are listed. The first line of output shows the version of the shell which compiled the file and how the file will be used (i.e. by reading it directly or by mapping it into memory). With arguments, nothing is output and the return value is set to zero if definitions for all names were found in the compiled file, and non-zero if the definition for at least one name was not found.
Other options:
When compiling scripts instead of autoloadable functions, it is often desirable to use this option; otherwise the whole file, including the code to define functions which have already been defined, will remain mapped, consequently wasting memory.
The created file always contains two versions of the compiled format, one for big-endian machines and one for small-endian machines. The upshot of this is that the compiled file is machine independent and if it is read or mapped, only one half of the file is actually used (and mapped).
Without arguments the names of all currently loaded binary modules are printed. The -L option causes this list to be in the form of a series of zmodload commands. Forms with arguments are:
The named module is searched for in the same way a command is, using $module_path instead of $path. However, the path search is performed even when the module name contains a `/', which it usually does. There is no way to prevent the path search.
With -u, zmodload unloads modules. The same name must be given that was given when the module was loaded, but it is not necessary for the module to exist in the filesystem. The -i option suppresses the error if the module is already unloaded (or was never loaded).
Each module has a boot and a cleanup function. The module will not be loaded if its boot function fails. Similarly a module can only be unloaded if its cleanup function runs successfully.
With -d and one argument, all dependencies for that module are listed. With -d and no arguments, all module dependencies are listed. This listing is by default in a Makefile-like format. The -L option changes this format to a list of zmodload -d commands.
If -d and -u are both used, dependencies are removed. If only one argument is given, all dependencies for that module are removed.
With -ab and no arguments, all autoloaded builtins are listed, with the module name (if different) shown in parentheses after the builtin name. The -L option changes this format to a list of zmodload -a commands.
If -b is used together with the -u option, it removes builtins previously defined with -ab. This is only possible if the builtin is not yet loaded. -i suppresses the error if the builtin is already removed (or never existed).
If given no condition names, all defined names are listed (as a series of zmodload commands if the -L option is given).
The -uc option removes definitions for autoloaded conditions.
The existence of aliases for modules is completely independent of whether the name resolved is actually loaded as a module: while the alias exists, loading and unloading the module under any alias has exactly the same effect as using the resolved name, and does not affect the connection between the alias and the resolved name which can be removed either by zmodload -R or by redefining the alias. Chains of aliases (i.e. where the first resolved name is itself an alias) are valid so long as these are not circular. As the aliases take the same format as module names, they may include path separators: in this case, there is no requirement for any part of the path named to exist as the alias will be resolved first. For example, `any/old/alias' is always a valid alias.
Dependencies added to aliased modules are actually added to the resolved module; these remain if the alias is removed. It is valid to create an alias whose name is one of the standard shell modules and which resolves to a different module. However, if a module has dependencies, it will not be possible to use the module name as an alias as the module will already be marked as a loadable module in its own right.
Apart from the above, aliases can be used in the zmodload command anywhere module names are required. However, aliases will not be shown in lists of loaded modules with a bare `zmodload'.
Note that zsh makes no distinction between modules that were linked into the shell and modules that are loaded dynamically. In both cases this builtin command has to be used to make available the builtins and other things defined by modules (unless the module is autoloaded on these definitions). This is true even for systems that don't support dynamic loading of modules.
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