/usr/bin/bash: Difference between revisions

;<nowiki>complete [-abcdefgjksuv] [-o comp-option] [-DEI] [-A action] [-G globpat] [-W wordlist]</nowiki>

;<nowiki>complete -pr [-DEI] [name ...]</nowiki>

Specify  how arguments to each name should be completed.  If the -p option is supplied, or if no options are supplied, existing completion specifications are printed in a  way  that allows  them  to be reused as input.  The -r option removes a completion specification for each name, or, if no names are supplied, all completion specifications.  The -D option indicates  that  other  supplied options and actions should apply to the ``default'' command completion; that is, completion attempted on a command for which no completion has  previously  been  defined.  The  -E  option  indicates that other supplied options and actions should apply to ``empty'' command completion; that is, completion  attempted  on  a  blank line.  The  -I  option  indicates that other supplied options and actions should apply to completion on the initial non-assignment word on the line, or after  a  command  delimiter such  as  ;  or |, which is usually command name completion.  If multiple options are supplied, the -D option takes precedence over -E, and both take precedence over -I.  If  any of  -D,  -E,  or  -I are supplied, any other name arguments are ignored; these completions only apply to the case specified by the option.

Other  options,  if  specified, have the following meanings.  The arguments to the -G, -W, and -X options (and, if necessary, the -P and -S options) should be quoted to protect them from expansion before the complete builtin is invoked.

::The  comp-option  controls  several  aspects of the compspec's behavior beyond the simple generation of completions.  comp-option may be one of:  

:::bashdefault  

:::plusdirs

::::After  any  matches  defined by the compspec are generated, directory name completion is attempted and any matches are added to the  results  of  the other actions.

::The action may be one of the following to generate a list of possible completions:

:::alias   

:::variable

::::Names of all shell variables.  May also be specified as -v.

::command is executed in a subshell environment, and its output is used as the  possible completions.

::The  shell  function  function is executed in the current shell environment.  When the function is executed, the first argument ($1) is the name of the command whose arguments  are  being  completed,  the second argument ($2) is the word being completed, and the third argument ($3) is the word preceding the word being completed on  the  current command line.  When it finishes, the possible completions are retrieved from the value of the COMPREPLY array variable.

::The pathname expansion pattern globpat is expanded to generate the  possible  completions.

::prefix  is  added at the beginning of each possible completion after all other options have been applied.

::suffix is appended to each possible completion after all other options  have  been applied.

::The  wordlist  is split using the characters in the IFS special variable as delimiters, and each resultant word is  expanded.  Shell  quoting  is  honored  within wordlist, in order to provide a mechanism for the words to contain shell metacharacters or characters in the value of IFS.  The possible completions are  the  members of the resultant list which match the word being completed.

::filterpat  is a pattern as used for pathname expansion.  It is applied to the list of possible completions generated by the preceding options and arguments, and each completion  matching filterpat is removed from the list.  A leading ! in filterpat negates the pattern; in this case, any completion not matching  filterpat  is  removed.

;<nowiki>typeset [-aAfFgiIlnrtux] [-p] [name[=value] ...]</nowiki>

Declare variables and/or give them attributes.  If no names are  given  then  display  the values  of  variables.  The -p option will display the attributes and values of each name. When -p is used with name arguments, additional options, other than -f  and  -F,  are  ignored.  When  -p  is  supplied without name arguments, it will display the attributes and values of all variables having the attributes specified by the additional options.  If  no other  options are supplied with -p, declare will display the attributes and values of all shell variables.  The -f option will restrict the display to shell functions.  The -F  option  inhibits  the display of function definitions; only the function name and attributes are printed.  If the extdebug shell option is enabled using shopt, the  source  file  name and  line  number where each name is defined are displayed as well.  The -F option implies -f.  The -g option forces variables to be created or modified at the  global  scope,  even when  declare  is executed in a shell function.  It is ignored in all other cases.  The -I option causes local variables to inherit the attributes (except the nameref attribute) and value  of any existing variable with the same name at a surrounding scope.  If there is no existing variable, the local variable is initially unset.  The following  options  can  be used to restrict output to variables with the specified attribute or to give variables attributes:

:::Each name is an indexed array variable (see Arrays above).

::Each name is an associative array variable (see Arrays above).

::Use function names only.

::The variable is treated as an integer; arithmetic evaluation (see ARITHMETIC EVALUATION above) is performed when the variable is assigned a value.

::When  the  variable is assigned a value, all upper-case characters are converted to lower-case.  The upper-case attribute is disabled.

::Give each name the nameref attribute, making it a name reference to  another  variable.  That  other  variable is defined by the value of name.  All references, assignments, and attribute modifications to name, except those using or changing  the -n attribute itself, are performed on the variable referenced by name's value.  The nameref attribute cannot be applied to array variables.

::Make names readonly.  These names cannot then be assigned values by subsequent  assignment statements or unset.

::Give  each name the trace attribute.  Traced functions inherit the DEBUG and RETURN traps from the calling shell.  The trace attribute has no special meaning for variables.

::When  the  variable is assigned a value, all lower-case characters are converted to upper-case.  The lower-case attribute is disabled.

::Mark names for export to subsequent commands via the environment.

;<nowiki>dirs [-clpv] [+n] [-n]</nowiki>

:Without options, displays the list of currently remembered directories.  The default  display  is on a single line with directory names separated by spaces.  Directories are added to the list with the pushd command; the popd command removes entries from the  list.  The current directory is always the first directory in the stack.

::Clears the directory stack by deleting all of the entries.

::Produces a listing using full pathnames; the default listing format uses a tilde to denote the home directory.

::Print the directory stack with one entry per line.

::Print the directory stack with one entry per line, prefixing each  entry  with  its index in the stack.

::Displays  the  nth  entry counting from the left of the list shown by dirs when invoked without options, starting with zero.

::Displays the nth entry counting from the right of the list shown by dirs  when  invoked without options, starting with zero.

;<nowiki>echo [-neE] [arg ...]</nowiki>

:Output the args, separated by spaces, followed by a newline.  The return status is  0  unless  a  write  error occurs.  If -n is specified, the trailing newline is suppressed.  If the -e option is given, interpretation of the following  backslash-escaped  characters  is enabled.  The  -E  option disables the interpretation of these escape characters, even on systems where they are interpreted by default.  The xpg_echo shell option may be  used  to dynamically  determine  whether  or  not  echo expands these escape characters by default. echo does not interpret -- to mean the end of options.  echo interprets the following  escape sequences:

::alert (bell)

::backspace

::suppress further output

::an escape character

::form feed

::new line

::carriage return

::horizontal tab

::vertical tab

::backslash

::the  eight-bit  character  whose  value is the octal value nnn (zero to three octal digits)

::the eight-bit character whose value is the hexadecimal value HH  (one  or  two  hex digits)

::the  Unicode  (ISO/IEC  10646)  character whose value is the hexadecimal value HHHH (one to four hex digits)

::the Unicode (ISO/IEC 10646) character whose value is the hexadecimal value HHHHHHHH (one to eight hex digits)

;<nowiki>help [-dms] [pattern]</nowiki>

:Display  helpful  information about builtin commands.  If pattern is specified, help gives detailed help on all commands matching pattern; otherwise help for all  the  builtins  and shell control structures is printed.

::Display a short description of each pattern

::Display the description of each pattern in a manpage-like format

::Display only a short usage synopsis for each pattern

;<nowiki>jobs -x command [ args ... ]</nowiki>

:The first form lists the active jobs.  The options have the following meanings:

::List process IDs in addition to the normal information.

::Display  information  only  about  jobs that have changed status since the user was last notified of their status.

::List only the process ID of the job's process group leader.

::Display only running jobs.

::Display only stopped jobs.

;<nowiki>readarray  [-d  delim]  [-n count] [-O origin] [-s count] [-t] [-u fd] [-C callback] [-c quantum] [array]</nowiki>

: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, if supplied, have the following meanings:

::The first character of delim is used to terminate each input line, rather than newline.  If delim is the empty string, mapfile will terminate a line when it reads a NUL character.

::Copy at most count lines.  If count is 0, all lines are copied.

::Begin assigning to array at index origin.  The default index is 0.

::Discard the first count lines read.

::Remove a trailing delim (default newline) from each line read.

::Read lines from file descriptor fd instead of the standard input.

::Evaluate callback each time quantum lines are read.  The -c option specifies  quantum.

::Specify the number of lines read between each call to callback.

;<nowiki>popd [-n] [+n] [-n]</nowiki>

:Removes  entries  from  the directory stack.  With no arguments, removes the top directory from the stack, and performs a cd to the new top directory.  Arguments, if supplied,  have the following meanings:

::Suppresses the normal change of directory when removing directories from the stack, so that only the stack is manipulated.

::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.

::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 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 printf(1) format specifications, printf interprets the following extensions:

::causes printf to expand backslash escape sequences in the corresponding argument in the same way as echo -e.

::causes  printf  to output the corresponding argument in a format that can be reused as shell input.

::causes printf to output the date-time string resulting from using datefmt as a format  string for strftime(3).  The corresponding argument is an integer representing the number of seconds since the epoch.  Two special argument values may be used: -1 represents  the current time, and -2 represents the time the shell was invoked.  If no argument is specified, conversion behaves as if -1 had been given.  This  is  an exception to the usual printf behavior.

;<nowiki>pushd [-n] [dir]</nowiki>

: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, pushd exchanges the top two directories and returns 0, unless the directory stack  is  empty.  Arguments,  if supplied, have the following meanings:

::Suppresses  the  normal  change of directory when rotating or adding directories to the stack, so that only the stack is manipulated.

::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.

::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.

::Adds dir to the directory stack at the top, making it the new current  working  di‐

rectory as if it had been supplied as the argument to the cd builtin.

;<nowiki>read [-ers] [-a aname] [-d delim] [-i text] [-n nchars] [-N nchars] [-p prompt] [-t timeout]  [-u fd] [name ...]</nowiki>

:One  line  is  read from the standard input, or from the file descriptor fd supplied as an argument to the -u option, split into words as described above under Word  Splitting,  and the  first  word is assigned to the first name, the second word to the second name, and so on.  If there are more words than names, the remaining words and their intervening  delimiters  are assigned to the last name.  If there are fewer words read from the input stream than names, the remaining names are assigned empty values.  The characters in IFS are used to  split the line into words using the same rules the shell uses for expansion (described above under Word Splitting).  The backslash character (\) may be used to remove  any  special meaning for the next character read and for line continuation.  Options, if supplied, have the following meanings:

::The words are assigned to sequential indices of the array variable aname,  starting at 0.  aname is unset before any new values are assigned.  Other name arguments are ignored.

::The first character of delim is used to terminate the input line, rather than  newline.  If delim is the empty string, read will terminate a line when it reads a NUL character.

::If the standard input is coming from a terminal, readline (see READLINE  above)  is used  to  obtain  the line.  Readline uses the current (or default, if line editing was not previously active) editing settings, but uses Readline's  default  filename completion.

::If  readline is being used to read the line, text is placed into the editing buffer before editing begins.

::read returns after reading nchars characters rather than  waiting  for  a  complete line  of input, but honors a delimiter if fewer than nchars characters are read before the delimiter.

::read returns after reading exactly nchars characters rather than waiting for a complete  line of input, unless EOF is encountered or read times out.  Delimiter characters encountered in the input are not treated specially and do not cause read  to return until nchars characters are read.  The result is not split on the characters in IFS; the intent is that the variable is assigned  exactly  the  characters  read (with the exception of backslash; see the -r option below).

::Display  prompt on standard error, without a trailing newline, before attempting to read any input.  The prompt is displayed only if input is coming from a terminal.

::Backslash does not act as an escape character.  The backslash is considered  to  be part  of the line.  In particular, a backslash-newline pair may not then be used as a line continuation.

::Silent mode.  If input is coming from a terminal, characters are not echoed.

::Cause read to time out and return failure if a complete line of input (or a  specified  number  of  characters) is not read within timeout seconds.  timeout may be a decimal number with a fractional portion following the decimal point.  This  option is  only effective if read is reading input from a terminal, pipe, or other special file; it has no effect when reading from regular files.  If read  times  out,  read saves  any  partial  input read into the specified variable name.  If timeout is 0, read returns immediately, without trying to read any data.  The exit status is 0 if input  is available on the specified file descriptor, non-zero otherwise.  The exit status is greater than 128 if the timeout is exceeded.

::Read input from file descriptor fd.

;<nowiki>set [+abefhkmnptuvxBCEHPT] [+o option-name] [arg ...]</nowiki>

:Without options, the name and value of each shell variable are displayed in a format  that can  be  reused  as input for setting or resetting the currently-set variables.  Read-only variables cannot be reset.  In posix mode, only shell variables are listed.  The output is sorted  according  to  the  current locale.  When options are specified, they set or unset shell attributes.  Any arguments remaining after option processing are treated  as  values for the positional parameters and are assigned, in order, to $1, $2, ...  $n.  Options, if specified, have the following meanings:

::Each variable or function that is created or modified is given the  export  attribute and marked for export to the environment of subsequent commands.

::Report  the  status  of terminated background jobs immediately, rather than before the next primary prompt.  This is effective only when job control is enabled.

::Exit immediately if a pipeline (which may consist of a single simple  command),  a list,  or a compound command (see SHELL GRAMMAR above), exits with a non-zero status.  The shell does not exit if the command that fails is  part  of  the  command list  immediately  following  a while or until keyword, part of the test following the if or elif reserved words, part of any command executed in a && or || list except  the  command following the final && or ||, any command in a pipeline but the last, or if the command's return value is being inverted with !.  If  a  compound command  other  than a subshell returns a non-zero status because a command failed while -e was being ignored, the shell does not exit.  A trap on ERR,  if  set,  is executed before the shell exits.  This option applies to the shell environment and each subshell environment separately (see COMMAND  EXECUTION  ENVIRONMENT  above), and may cause subshells to exit before executing all the commands in the subshell.

::If  a  compound  command or shell function executes in a context where -e is being ignored, none of the commands executed within the  compound  command  or  function body will be affected by the -e setting, even if -e is set and a command returns a failure status.  If a compound command or shell function sets -e  while  executing in  a context where -e is ignored, that setting will not have any effect until the compound command or the command containing the function call completes.

::Disable pathname expansion.

::Remember the location of commands as they are looked up for  execution.  This  is enabled by default.

::All  arguments  in the form of assignment statements are placed in the environment for a command, not just those that precede the command name.

::Monitor mode.  Job control is enabled.  This option is on by default for  interactive shells on systems that support it (see JOB CONTROL above).  All processes run in a separate process group.  When a background job completes, the shell prints  a line containing its exit status.

::Read  commands  but do not execute them.  This may be used to check a shell script for syntax errors.  This is ignored by interactive shells.

::The option-name can be one of the following:

::allexport

:::Same as -x.

::If  -o  is  supplied  with  no  option-name, the values of the current options are printed.  If +o is supplied with no option-name,  a  series  of  set  commands  to recreate the current option settings is displayed on the standard output.

::Turn  on privileged mode.  In this mode, the $ENV and $BASH_ENV files are not processed, shell functions are not inherited from the environment, and the SHELLOPTS, BASHOPTS, CDPATH, and GLOBIGNORE variables, if they appear in the environment, are ignored.  If the shell is started with the effective user (group) id not equal  to the  real  user  (group)  id, and the -p option is not supplied, these actions are taken and the effective user id is set to the real user id.  If the -p  option  is supplied  at startup, the effective user id is not reset.  Turning this option off causes the effective user and group ids to be set to the real user and group ids.

::Exit after reading and executing one command.

::Treat unset variables and parameters other than the special parameters "@" and "*" as  an error when performing parameter expansion.  If expansion is attempted on an unset variable or parameter, the shell prints an error message, and, if not interactive, exits with a non-zero status.

::Print shell input lines as they are read.

::After expanding each simple command, for command, case command, select command, or arithmetic for command, display the expanded value of PS4, followed by the command and its expanded arguments or associated word list.

::The shell performs brace expansion (see Brace Expansion above).  This is on by default.

::If set, bash does not overwrite an existing file with the >, >&, and <>  redirection operators.  This may be overridden when creating output files by using the redirection operator >| instead of >.

::If set, any trap on ERR is inherited by shell  functions,  command  substitutions, and commands executed in a subshell environment.  The ERR trap is normally not inherited in such cases.

::Enable !  style history substitution.  This option is on by default when the shell is interactive.

::If  set, the shell does not resolve symbolic links when executing commands such as cd that change the current working directory.  It  uses  the  physical  directory structure instead.  By default, bash follows the logical chain of directories when performing commands which change the current directory.

::If set, any traps on DEBUG and RETURN are inherited by  shell  functions,  command substitutions, and commands executed in a subshell environment.  The DEBUG and RETURN traps are normally not inherited in such cases.

::If no arguments follow this option, then  the  positional  parameters  are  unset.Otherwise, the positional parameters are set to the args, even if some of them begin with a -.

::Signal the end of options, cause all remaining args to be assigned  to  the  positional  parameters.  The -x and -v options are turned off.  If there are no args, the positional parameters remain unchanged.

;<nowiki>shopt [-pqsu] [-o] [optname ...]</nowiki>

:Toggle  the  values  of settings controlling optional shell behavior.  The settings can be either those listed below, or, if the -o option is used, those available with the  -o  option  to  the  set builtin command.  With no options, or with the -p option, a list of all settable options is displayed, with an indication of whether or not each is set;  if  optnames  are supplied, the output is restricted to those options.  The -p option causes output to be displayed in a form that may be reused as input.  Other options have the following meanings:

::Enable (set) each optname.

::Disable (unset) each optname.

::Suppresses normal output (quiet mode); the return status indicates whether the optname is set or unset.  If multiple optname arguments are given with -q, the  return status is zero if all optnames are enabled; non-zero otherwise.

::Restricts  the  values  of optname to be those defined for the -o option to the set builtin.

:The return status when listing options is zero if all optnames are enabled, non-zero  otherwise.  When setting or unsetting options, the return status is zero unless an optname is not a valid shell option.

;;cdable_vars

;<nowikI>suspend [-f]</nowiki>

;test expr

;<nowiki>[ expr ]</nowiki>

;times   

;<nowiki>trap [-lp] [[arg] sigspec ...]</nowiki>

;<nowiki>type [-aftpP] name [name ...]</nowiki>

;<nowiki>ulimit [-HS] -a</nowiki>

;<nowiki>ulimit [-HS] [-bcdefiklmnpqrstuvxPRT [limit]]</nowiki>

;<nowiki>umask [-p] [-S] [mode]</nowiki>

;<nowiki>unalias [-a] [name ...]</nowiki>

;<nowiki>unset [-fv] [-n] [name ...]</nowiki>

;<nowiki>wait [-fn] [-p varname] [id ...]</nowiki>

== SHELL COMPATIBILITY MODE ==