zshmisc

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NAME

       zshmisc - Everything and then some


SYNOPSIS

       Everything I haven't put somewhere else


SHELL GRAMMAR

       A  simple  command  is  a  sequence  of optional parameter
       assignments  followed  by  blank-separated   words,   with
       optional redirections interspersed.  The first word is the
       command to be executed, and the remaining words,  if  any,
       are arguments to the command.  If a command name is given,
       the parameter assignments modify the  environment  of  the
       command  when  it is executed.  The value of a simple com-
       mand is its exit status, or 128 plus the signal number  if
       terminated by a signal.

       If  a  simple  command is preceded by the word exec, it is
       executed in the parent shell without forking.  If preceded
       by command, the command word is taken to be the name of an
       external command, rather than a shell function or builtin.
       If  preceded  by  noglob,  filename generation is not per-
       formed on any of the words.  If preceded by a -, the  com-
       mand is executed with a - prepended to its argv[0] string.
       If preceded by nocorrect, spelling correction is not  done
       on any of the words.

       A pipeline is a sequence of one or more commands separated
       by | or |&.  |& is shorthand for  2>&1  |.   The  standard
       output  of each command is connected to the standard input
       of the next command in the pipeline.

       The value of a pipeline is the value of the last  command.
       If  a  pipeline  is  preceded  by  a  !, the value of that
       pipeline is the logical NOT of the value of the last  com-
       mand.

       If  a  pipeline is preceded by coproc, it is executed as a
       coprocess; a two-way pipe is established  between  it  and
       the parent shell.  The shell can read from or write to the
       coprocess by means of the >&p and <&p  redirection  opera-
       tors.

       A sublist is a sequence of one or more pipelines separated
       by && or ||.  If two pipelines are separated  by  &&,  the
       second  pipeline is executed only if the first is success-
       ful (returns a zero value).  If two  pipelines  are  sepa-
       rated  by  ||, the second is executed only if the first is
       unsuccessful (returns a nonzero  value).   Both  operators
       have equal precedence and are left associative.

       A list is a sequence of one or more sublists separated by,
       and optionally terminated by, ;, &, or  a  newline.   Nor-
       mally  the  shell  waits  for  each  list to finish before
       executing the next one.  If a list is terminated by  a  &,
       the shell executes it in the background, and does not wait
       for it to finish.

       A complex command is one of the following:

              for name [ in word ... ]
              do list
              done   Expand the list of words, and set the param-
                     eter name to each of them in turn, executing
                     list each time.  If the in word is  omitted,
                     use the positional parameters instead of the
                     words.

              for name [ in word ... ] ; sublist
                     This is a shorthand for for.  Though it  may
                     cause  confusion,  it is included for conve-
                     nience; its use in scripts  is  discouraged,
                     unless  sublist  is  a command of the form {
                     list }.

              foreach name ( word ... )
              list
              end    Another form of for.

              for name in word ...
              {
              list
              }      Another form of for.

              for name ( word ... ) {
              list
              }      Another form  of  for:   this  requires  the
                     option CSH_JUNKIE_PAREN.

              for name ( word ... ) sublist
                     Another  form  of  for:   this also requires
                     CSH_JUNKIE_PAREN.

              select name [ in word ... ]
              do list
              done   Print the set of words, each preceded  by  a
                     number.   If the in word is omitted, use the
                     positional parameters.  The  PROMPT3  prompt
                     is  printed and a line is read from standard
                     input.  If this line consists of the  number
                     of one of the listed words, then the parame-
                     ter name is set to the word corresponding to
                     this  number.   If  this  line is empty, the
                     selection list is printed again.  Otherwise,
                     the  value  of  the parameter name is set to
                     null.  The contents of the  line  read  from
                     standard  input  is  saved  in the parameter
                     REPLY.  list is executed for each  selection
                     until a break or end-of-file is encountered.

              select name [ in word ] ; sublist
                     A short form of select.

              case word in [ pattern ) list ;; ] ...  esac
                     Execute the list associated with  the  first
                     pattern that matches word, if any.  The form
                     of the patterns is the same as that used for
                     filename  generation.   See Filename Genera-
                     tion below.

              case word { [ pattern ) list ;; ] ...  }
                     Another form of case.

              if list
              then list
              [ elif list ; then list ] ...
              [ else list ]
              fi     The if list is executed, and, if it  returns
                     a  zero  exit  status, the then list is exe-
                     cuted.  Otherwise, the elif list is executed
                     and,  if its value is zero, the then list is
                     executed.   If  each   elif   list   returns
                     nonzero, the else list is executed.

              if ( list ) sublist
                     A  short  form  of  if:   this  requires the
                     option CSH_JUNKIE_PAREN.

              if ( list ) {
              list
              } elif ( list ) {
              list
              } ... else {
              list
              }      An alternative form of if.  The  parentheses
                     surrounding  list can be omitted if the only
                     command in the list is a conditional expres-
                     sion  of  the  form  [[  exp ]] (see below).
                     This form also requires CSH_JUNKIE_PAREN.

              while list
              do list
              done   Execute the do list as  long  as  the  while
                     list returns a zero exit status.

              while ( list ) {
              list
              }      An alternative form of while:  this requires
                     the option CSH_JUNKIE_PAREN.

              until list

              do list
              done   Execute the do list as long  as  until  list
                     returns a nonzero exit status.

              repeat word
              do list
              done   word  is  expanded  and treated as an arith-
                     metic expression, which must evaluate  to  a
                     number n.  list is then executed n times.

              repeat word sublist
                     This is a short form of repeat.

              ( list )
                     Execute list in a subshell.

              { list }
                     Execute list.

              function word [ () ] ... { list }
              word ... () { list }
              word ... () sublist
                     Define a function which is referenced by any
                     one of word.  Normally,  only  one  word  is
                     provided;  multiple  words  are usually only
                     useful for setting traps.  The body  of  the
                     function  is  the  list between the { and }.
                     See FUNCTIONS below.

              time [ pipeline ]
                     The pipeline is executed, and timing statis-
                     tics  are  reported on the standard error in
                     the form specified by the TIMEFMT parameter.
                     If  pipeline  is  omitted,  print statistics
                     about the shell process and its children.

              [[ exp ]]
                     Evaluates the conditional expression exp and
                     return  a  zero  exit  status if it is true.
                     See  Conditional  Expressions  below  for  a
                     description of exp.


RESERVED WORDS

       The  following words are recognized as reserved words when
       used as the first word  of  a  command  unless  quoted  or
       removed using the unalias builtin:

              do  done  esac  then elif else fi for case if while
              function repeat  time  until  exec  command  select
              coproc noglob - nocorrect foreach end


COMMENTS

       In  noninteractive  shells,  or in interactive shells with
       the INTERACTIVE_COMMENTS option set, a word beginning with
       the  third  character  of  the histchars parameter (`#' by
       default) causes that word and all the following characters
       up to a newline to be ignored.


ALIASING

       Every  token in the shell input is checked to see if there
       is an alias defined for it.  If so, it is replaced by  the
       text  of  the  alias  if  it is in command position (if it
       could be the first word of a simple command),  or  if  the
       alias  is global.  If the text ends with a space, the next
       word in the shell input is treated as though  it  were  in
       command  position  for  purposes  of  alias expansion.  An
       alias is defined using the alias builtin;  global  aliases
       may be defined using the -g option to that builtin.

       Alias  substitution  is done on the shell input before any
       other substitution except  history  substitution.   There-
       fore,  if an alias is defined for the word foo, alias sub-
       stitution may be avoided by quoting part of the word, e.g.
       \foo.   But  there  is  nothing  to prevent an alias being
       defined for \foo as well.


QUOTING

       A character may be quoted (that  is,  made  to  stand  for
       itself) by preceding it with a \.  \ followed by a newline
       is ignored.  All characters enclosed  between  a  pair  of
       single  quotes ('') are quoted, except the first character
       of histchars ( `!' by default).   A  single  quote  cannot
       appear  within  single quotes.  Inside double quotes (""),
       parameter and command substitution occurs,  and  \  quotes
       the characters \, `, ", and $.


REDIRECTION

       Before  a command is executed, its input and output may be
       redirected.  The following may appear anywhere in a simple
       command  or may precede or follow a complex command.  Sub-
       stitution occurs before  word  is  used  except  as  noted
       below.   If  the  result  of substitution on word produces
       more than one filename, redirection occurs for each  sepa-
       rate filename in turn.

       <word  Open file word as standard input.

       >word  Open  file  word  as  standard output.  If the file
              does not exist then it is  created.   If  the  file
              exists,  and  the  NO_CLOBBER  option  is set, this
              causes an error; otherwise, it is truncated to zero
              length.

       >| word
       >! word
              Same  as  >,  except  that the file is truncated to
              zero length if it exists,  even  if  NO_CLOBBER  is
              set.

       >>word Open  file  word  as  standard output.  If the file
              exists then output is appended to it.  If the  file
              does  not  exist, and the NO_CLOBBER option is set,
              this causes an error; otherwise, the file  is  cre-
              ated.

       >>| word
       >>! word
              Same  as  >>, except that the file is created if it
              does not exist, even if NO_CLOBBER is set.

       <<[-] word
              The shell input is read up to a line  that  is  the
              same  as  word, or to an end-of-file.  No parameter
              substitution, command substitution or filename gen-
              eration  is performed on word.  The resulting docu-
              ment, called a here-document, becomes the  standard
              input.   If  any  character  of word is quoted with
              single or double quotes or a \,  no  interpretation
              is  placed  upon  the  characters  of the document.
              Otherwise,  parameter  and   command   substitution
              occurs,  \  followed by a newline is removed, and \
              must be used to quote the characters \, $,  `,  and
              the  first character of word.  If <<- is used, then
              all leading tabs are stripped from  word  and  from
              the document.

       <<<word
              Perform shell expansion on word and pass the result
              to standard input.

       <&digit
              The standard input is duplicated from file descrip-
              tor  digit  (see  dup(2)).   Similarly for standard
              output using >&digit.

       >&word Same as >word 2>&1.

       >>&word
              Same as >>word 2>&1.

       <&-    Close the standard input.

       >&-    Close the standard output.

       <&p    The input from the coprocess is moved to the  stan-
              dard input.

       >&p    The  output  to the coprocess is moved to the stan-
              dard output.

       If one of the above is preceded by a digit, then the  file
       descriptor  referred  to  is  that  specified by the digit
       (instead of the default 0  or  1).   The  order  in  which
       redirections  are  specified  is  significant.   The shell
       evaluates each redirection in terms of the (file  descrip-
       tor,  file)  association  at  the time of evaluation.  For
       example:

              ... 1>fname 2>&1

       first associates file descriptor 1 with  file  fname.   It
       then associates file descriptor 2 with the file associated
       with file descriptor 1 (that is, fname).  If the order  of
       redirections  were  reversed,  file  descriptor 2 would be
       associated with the terminal (assuming file  descriptor  1
       had  been)  and then file descriptor 1 would be associated
       with file fname.

       If the user tries to open a file  descriptor  for  writing
       more  than  once, the shell opens the file descriptor as a
       pipe to a process that copies its input to all the  speci-
       fied outputs, similar to tee(1).  Thus:

              date >foo >bar

       writes the date to two files, named "foo" and "bar".  Note
       that a pipe is an implicit indirection; thus

              date >foo | cat

       writes the date to the file "foo", and also  pipes  it  to
       cat.

       If  the  user  tries to open a file descriptor for reading
       more than once, the shell opens the file descriptor  as  a
       pipe  to a process that copies all the specified inputs to
       its output in the  order  specified,  similar  to  cat(1).
       Thus

              sort <foo <fubar

       or even

              sort <f{oo,ubar}

       is  equivalent  to "cat foo fubar | sort".  Similarly, you
       can do

              echo exit 0 >> *.sh

       Note that a pipe is in implicit indirection; thus

              cat bar | sort <foo

       is equivalent to "cat bar foo | sort" (note the  order  of
       the inputs).

       If  a  simple  command consists of one or more redirection
       operators and zero or more parameter assignments,  but  no
       command name, the command cat is assumed.  Thus

              < file

       prints the contents of file.

       If  a  command  is  followed  by  & and job control is not
       active, then the default standard input for the command is
       the  empty file /dev/null.  Otherwise, the environment for
       the execution of a command contains the  file  descriptors
       of the invoking shell as modified by input/output specifi-
       cations.


COMMAND EXECUTION

       If a command name contains no slashes, the shell  attempts
       to  locate  it.   If there exists a shell function by that
       name, the function is invoked as described below in  FUNC-
       TIONS.   If there exists a shell builtin by that name, the
       builtin is invoked.

       Otherwise, the shell searches each element of path  for  a
       directory  containing an executable file by that name.  If
       the search is unsuccessful, the shell prints an error mes-
       sage and returns a nonzero exit status.

       If  execution  fails because the file is not in executable
       format, and the file is not a directory, it is assumed  to
       be  a shell script.  /bin/sh is spawned to execute it.  If
       the program is a file beginning with #!, the remainder  of
       the  first  line specifies an interpreter for the program.
       The shell will execute the specified interpreter on  oper-
       ating systems that do not handle this executable format in
       the kernel.


FUNCTIONS

       The function reserved word is used to define  shell  func-
       tions.  Shell functions are read in and stored internally.
       Alias names are resolved when the function is read.  Func-
       tions are executed like commands with the arguments passed
       as positional parameters.  (See Execution below).

       Functions execute in the same process as  the  caller  and
       share  all  files  and  present working directory with the
       caller.  A trap on EXIT set inside a function is  executed
       after  the  function  completes  in the environment of the
       caller.

       The return builtin is used to return from function  calls.

       Function  identifiers  can  be  listed  with the functions
       builtin.  Functions can be undefined with  the  unfunction
       builtin.
       The  following functions, if defined, have special meaning
       to the shell:

       chpwd  Executed whenever the current working directory  is
              changed.
       precmd Executed before each prompt.
       periodic
              If  the  parameter  PERIOD is set, this function is
              executed  every  PERIOD  seconds,  just  before   a
              prompt.
       TRAPxxx
              If defined and non-null, this function will be exe-
              cuted whenever the shell catches a  signal  SIGxxx,
              where  xxx  is  a  signal name as specified for the
              kill builtin (see below).  The signal  number  will
              be  passed  as the first parameter to the function.
              In addition, TRAPZERR is executed whenever  a  com-
              mand  has a non-zero exit status, TRAPDEBUG is exe-
              cuted after each command, and TRAPEXIT is  executed
              when  the shell exits, or when the current function
              exits if defined inside a function.  If a  function
              of  this  form  is  defined and null, the shell and
              processes spawned by it will ignore SIGxxx.


JOBS

       If the MONITOR option is set, an interactive shell associ-
       ates  a  job with each pipeline.  It keeps a table of cur-
       rent jobs, printed by the jobs command, and  assigns  them
       small  integer  numbers.   When  a  job  is  started asyn-
       chronously with &, the shell prints  a  line  which  looks
       like:

            [1] 1234

       indicating  that  the job which was started asynchronously
       was job number 1 and had one  (top-level)  process,  whose
       process id was 1234.

       If you are running a job and wish to do something else you
       may hit the key ^Z (control-Z) which sends a  TSTP  signal
       to the current job.  The shell will then normally indicate
       that the job  has  been  `suspended',  and  print  another
       prompt.   You  can  then manipulate the state of this job,
       putting it in the background with the bg command,  or  run
       some other commands and then eventually bring the job back
       into the foreground with the foreground command fg.  A  ^Z
       takes  effect immediately and is like an interrupt in that
       pending output and unread input are discarded when  it  is
       typed.

       A job being run in the background will suspend if it tries
       to read from the terminal.  Background jobs  are  normally
       allowed  to  produce  output,  but this can be disabled by
       giving the command ``stty tostop''.  If you set  this  tty
       option, then background jobs will suspend when they try to
       produce output like they do when they try to read input.

       There are several ways to refer to jobs in the  shell.   A
       job can be referred to by the process id of any process of
       the job or by one of the following:
       %number
              The job with the given number.
       %string
              Any job whose command line begins with string.
       %?string
              Any job whose command line contains string.
       %%     Current job.
       %+     Equivalent to %%.
       %-     Previous job.

       The shell learns immediately whenever  a  process  changes
       state.   It  normally  informs  you whenever a job becomes
       blocked so that  no  further  progress  is  possible.   If
       notify  is not set, it waits until just before it prints a
       prompt before it informs you.

       When the monitor mode is on, each background job that com-
       pletes triggers any trap set for CHLD.

       When  you try to leave the shell while jobs are running or
       suspended, you will be warned  that  `You  have  suspended
       (running) jobs.'  You may use the jobs command to see what
       they are.  If you do  this  or  immediately  try  to  exit
       again, the shell will not warn you a second time; the sus-
       pended jobs will be terminated, and the running jobs  will
       be sent a SIGHUP signal.  To avoid having the shell termi-
       nate the running jobs, either use the nohup(1) command  or
       the disown builtin (see below).


SIGNALS

       The  INT  and  QUIT  signals  for  an  invoked command are
       ignored if the command is followed by & and the job  MONI-
       TOR  option  is  not  active.  Otherwise, signals have the
       values inherited by the shell from its parent (but see the
       TRAPxxx special function above).


ARITHMETIC EVALUATION

       An  ability to perform integer arithmetic is provided with
       the builtin let.  Evaluations  are  performed  using  long
       arithmetic.  Constants with a leading 0 are interpreted as
       octal numbers.  A leading 0x or  0X  denotes  hexadecimal.
       Otherwise,  numbers are of the form [base#]n where base is
       a decimal number between two and  thirty-six  representing
       the  arithmetic  base  and n is a number in that base (for
       example, `16#ff' is 255 in hexadecimal).  If base is omit-
       ted then base 10 is used.  For backwards compatibility the
       form `[16]ff' is also accepted.

       An arithmetic expression  uses  nearly  the  same  syntax,
       precedence,  and  associativity  of expressions in C.  The
       following operators are supported  (listed  in  decreasing
       order of precedence):

              + - ! ~ ++ --
                     unary  plus/minus,  logical NOT, complement,
                     {pre,post}{in,de}crement
              << >>  bitwise shift left, right
              &      bitwise AND
              ^      bitwise XOR
              |      bitwise OR
              **     exponentiation
              * / %  multiplication, division,  modulus  (remain-
                     der)
              + -    addition, subtraction
              < > <= >=
                     comparison
              == !=  equality and inequality
              &&     logical AND
              || ^^  logical OR, XOR
              ? :    ternary operator
              = += -= *= /= %= &= ^= |= <<= >>= &&= ||= ^^= **=
                     assignment
              ,      comma operator

       The  operators  &&, ||, &&=, and ||= are short-circuiting,
       and only one of the latter two expressions  in  a  ternary
       operator is evaluated.  Note the precedence of the bitwise
       AND, OR, and XOR operators.

       An expression of the form #\x where  x  is  any  character
       gives  the ascii value of this character and an expression
       of the form #foo gives the ascii value of the first  char-
       acter of the value of the parameter foo.

       Named  parameters and subscripted arrays can be referenced
       by name within an arithmetic expression without using  the
       parameter substitution syntax.

       An  internal  integer  representation of a named parameter
       can be specified with  the  integer  builtin.   Arithmetic
       evaluation is performed on the value of each assignment to
       a named parameter declared integer in this manner.

       Since many of the arithmetic operators require quoting, an
       alternative  form of the let command is provided.  For any
       command which begins with a ((, all the characters until a
       matching )) are treated as a quoted expression.  More pre-
       cisely, ((...))  is equivalent to let "...".


CONDITIONAL EXPRESSIONS

       A conditional expression is used with the [[ compound com-
       mand  to  test attributes of files and to compare strings.
       Each expression can be constructed from one or more of the
       following unary or binary expressions:
       -a file
              true if file exists.
       -b file
              true if file exists and is a block special file.
       -c file
              true  if  file  exists  and  is a character special
              file.
       -d file
              true if file exists and is a directory.
       -e file
              true if file exists.
       -f file
              true if file exists and is an ordinary file.
       -g file
              true if file exists and has its setgid bit set.
       -h file
              true if file exists and is a symbolic link.
       -k file
              true if file exists and has its sticky bit set.
       -n string
              true if length of string is non-zero.
       -o option
              true if option named option is on.
       -p file
              true if file exists and is a fifo special file or a
              pipe.
       -r file
              true if file exists and is readable by current pro-
              cess.
       -s file
              true if file exists and has size greater than zero.
       -t fd  true if file descriptor number fd is open and asso-
              ciated with a terminal device.  (note:  fd  is  not
              optional)
       -u file
              true if file exists and has its setuid bit set.
       -w file
              true if file exists and is writable by current pro-
              cess.
       -x file
              true if file exists and is  executable  by  current
              process.   If  file exists and is a directory, then
              the current process has permission to search in the
              directory.
       -z string
              true if length of string is zero.
       -L file
              true if file exists and is a symbolic link.
       -O file
              true  if  file exists and is owned by the effective
              user id of this process.

       -G file
              true if file  exists  and  its  group  matches  the
              effective group id of this process.
       -S file
              true if file exists and is a socket.
       file1 -nt file2
              true if file1 exists and is newer than file2.
       file1 -ot file2
              true if file1 exists and is older than file2.
       file1 -ef file2
              true if file1 and file2 exist and refer to the same
              file.
       string = pattern
              true if string matches pattern.
       string != pattern
              true if string does not match pattern.
       string1 < string2
              true if string1 comes before string2 based on ASCII
              value of their characters.
       string1 > string2
              true  if string1 comes after string2 based on ASCII
              value of their characters.
       exp1 -eq exp2
              true if exp1 is equal to exp2.
       exp1 -ne exp2
              true if exp1 is not equal to exp2.
       exp1 -lt exp2
              true if exp1 is less than exp2.
       exp1 -gt exp2
              true if exp1 is greater than exp2.
       exp1 -le exp2
              true if exp1 is less than or equal to exp2.
       exp1 -ge exp2
              true if exp1 is greater than or equal to exp2.
       ( exp )
              true if exp is true.
       ! exp  true if exp is false.
       exp1 && exp2
              true if exp1 and exp2 are both true.
       exp1 || exp2
              true if either exp1 or exp2 is true.

       In each of the above expressions, if file is of  the  form
       /dev/fd/n, where n is an integer, then the test applied to
       the open file whose descriptor number is n,  even  if  the
       underlying  system does not support the /dev/fd directory.
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