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       zshparam - zsh parameters


       A  parameter  has  a name, a value, and a number of attributes.  A name
       may be any sequence of alphanumeric characters and underscores, or  the
       single  characters `*', `@', `#', `?', `-', `$', or `!'.  The value may
       be a scalar (a string), an integer, an array (indexed numerically),  or
       an  associative array (an unordered set of name-value pairs, indexed by
       name).  To declare the type of a parameter, or to assign  a  scalar  or
       integer value to a parameter, use the typeset builtin.

       The  value  of  a  scalar  or integer parameter may also be assigned by


       If the integer attribute, -i, is set for name, the value is subject  to
       arithmetic  evaluation.   Furthermore,  by  replacing  `=' with `+=', a
       parameter can  be  added  or  appended  to.   See  the  section  `Array
       Parameters' for additional forms of assignment.

       To  refer to the value of a parameter, write `$name' or `${name}'.  See
       Parameter Expansion in zshexpn(1) for complete details.

       In the parameter lists that follow, the mark `<S>' indicates  that  the
       parameter  is  special.   Special  parameters  cannot  have  their type
       changed or their readonly  attribute  turned  off,  and  if  a  special
       parameter  is  unset, then later recreated, the special properties will
       be retained.  `<Z>' indicates that the parameter does  not  exist  when
       the shell initializes in sh or ksh emulation mode.


       To assign an array value, write one of:

              set -A name value ...
              name=(value ...)

       If  no  parameter  name exists, an ordinary array parameter is created.
       If the parameter name exists and is a scalar, it is replaced by  a  new
       array.  Ordinary array parameters may also be explicitly declared with:

              typeset -a name

       Associative arrays must be declared before assignment, by using:

              typeset -A name

       When name refers to an associative array, the list in an assignment  is
       interpreted as alternating keys and values:

              set -A name key value ...
              name=(key value ...)

       Every  key  must  have a value in this case.  Note that this assigns to
       the entire array, deleting any elements that do not appear in the list.

       To create an empty array (including associative arrays), use one of:

              set -A name

   Array Subscripts
       Individual  elements  of an array may be selected using a subscript.  A
       subscript of the form `[exp]' selects the single element exp, where exp
       is  an  arithmetic  expression  which  will  be  subject  to arithmetic
       expansion as if it were surrounded by  `$((...))'.   The  elements  are
       numbered beginning with 1, unless the KSH_ARRAYS option is set in which
       case they are numbered from zero.

       Subscripts may be used inside braces used to delimit a parameter  name,
       thus  `${foo[2]}' is equivalent to `$foo[2]'.  If the KSH_ARRAYS option
       is set, the braced form is  the  only  one  that  works,  as  bracketed
       expressions otherwise are not treated as subscripts.

       If  the  KSH_ARRAYS  option  is not set, then by default accesses to an
       array element with a subscript that evaluates to zero return  an  empty
       string,  while  an  attempt  to  write such an element is treated as an
       error.  For backward compatibility the KSH_ZERO_SUBSCRIPT option can be
       set  to  cause  subscript  values  0  and  1  to be equivalent; see the
       description of the option in zshoptions(1).

       The same subscripting syntax is used  for  associative  arrays,  except
       that  no  arithmetic expansion is applied to exp.  However, the parsing
       rules for arithmetic expressions still apply,  which  affects  the  way
       that  certain special characters must be protected from interpretation.
       See Subscript Parsing below for details.

       A subscript of the form `[*]' or `[@]' evaluates to all elements of  an
       array;  there  is no difference between the two except when they appear
       within double  quotes.   `"$foo[*]"'  evaluates  to  `"$foo[1]  $foo[2]
       ..."', whereas `"$foo[@]"' evaluates to `"$foo[1]" "$foo[2]" ...'.  For
       associative arrays, `[*]' or `[@]' evaluate to all the  values,  in  no
       particular order.  Note that this does not substitute the keys; see the
       documentation for the `k'  flag  under  Parameter  Expansion  Flags  in
       zshexpn(1) for complete details.  When an array parameter is referenced
       as `$name' (with no subscript) it evaluates to `$name[*]',  unless  the
       KSH_ARRAYS  option  is  set  in which case it evaluates to `${name[0]}'
       (for an associative array, this means the value of the key  `0',  which
       may not exist even if there are values for other keys).

       A subscript of the form `[exp1,exp2]' selects all elements in the range
       exp1 to exp2, inclusive. (Associative arrays are unordered, and  so  do
       not  support  ranges.) If one of the subscripts evaluates to a negative
       number, say -n, then the nth element from the end of the array is used.
       Thus `$foo[-3]' is the third element from the end of the array foo, and
       `$foo[1,-1]' is the same as `$foo[*]'.

       Subscripting may also be performed on non-array values, in  which  case
       the  subscripts  specify  a substring to be extracted.  For example, if
       FOO is set to `foobar', then `echo $FOO[2,5]' prints `ooba'.

   Array Element Assignment
       A subscript may be used on the left side of an assignment like so:


       In this form of assignment the element or range  specified  by  exp  is
       replaced  by  the  expression  on the right side.  An array (but not an
       associative array) may be created by assignment to a range or  element.
       Arrays  do  not nest, so assigning a parenthesized list of values to an
       element or range changes the number of elements in the array,  shifting
       the  other  elements  to  accommodate  the  new  values.   (This is not
       supported for associative arrays.)

       This syntax also works as an argument to the typeset command:

              typeset "name[exp]"=value

       The  value  may  not  be  a  parenthesized  list  in  this  case;  only
       single-element  assignments may be made with typeset.  Note that quotes
       are  necessary  in  this  case  to  prevent  the  brackets  from  being
       interpreted  as  filename  generation operators.  The noglob precommand
       modifier could be used instead.

       To delete an element of an ordinary array, assign `()' to that element.
       To delete an element of an associative array, use the unset command:

              unset "name[exp]"

   Subscript Flags
       If  the  opening  bracket,  or  the  comma in a range, in any subscript
       expression is directly followed by an opening parenthesis,  the  string
       up  to the matching closing one is considered to be a list of flags, as
       in `name[(flags)exp]'.

       The flags s, n and b take an argument; the delimiter is shown below  as
       `:',  but  any  character,  or  the  matching  pairs  `(...)', `{...}',
       `[...]', or `<...>', may be used.

       The flags currently understood are:

       w      If the parameter subscripted is a scalar then  this  flag  makes
              subscripting  work  on words instead of characters.  The default
              word separator is whitespace.  This flag may not  be  used  with
              the i or I flag.

              This  gives  the string that separates words (for use with the w
              flag).  The delimiter character : is arbitrary; see above.

       p      Recognize the same escape sequences as the print builtin in  the
              string argument of a subsequent `s' flag.

       f      If  the  parameter  subscripted is a scalar then this flag makes
              subscripting work on lines  instead  of  characters,  i.e.  with
              elements  separated  by  newlines.   This  is  a  shorthand  for

       r      Reverse subscripting: if this flag is given, the exp is taken as
              a  pattern  and  the result is the first matching array element,
              substring or word (if the parameter is an  array,  if  it  is  a
              scalar,  or  if  it  is  a  scalar  and  the  `w' flag is given,
              respectively).  The subscript used is the number of the matching
              element, so that pairs of subscripts such as `$foo[(r)??,3]' and
              `$foo[(r)??,(r)f*]' are possible if  the  parameter  is  not  an
              associative  array.   If  the parameter is an associative array,
              only the value part of each pair is compared to the pattern, and
              the result is that value.

              If  a  search  through an ordinary array failed, the search sets
              the subscript to one past  the  end  of  the  array,  and  hence
              ${array[(r)pattern]} will substitute the empty string.  Thus the
              success of a search can be tested by using  the  (i)  flag,  for
              example (assuming the option KSH_ARRAYS is not in effect):

                     [[ ${array[(i)pattern]} -le ${#array} ]]

              If KSH_ARRAYS is in effect, the -le should be replaced by -lt.

              R      Like  `r',  but  gives  the  last match.  For associative
                     arrays, gives all  possible  matches.  May  be  used  for
                     assigning   to  ordinary  array  elements,  but  not  for
                     assigning to associative arrays.  On failure, for  normal
                     arrays  this  has  the  effect  of  returning the element
                     corresponding to subscript 0; this is empty unless one of
                     the   options  KSH_ARRAYS  or  KSH_ZERO_SUBSCRIPT  is  in

                     Note that in subscripts with both  `r'  and  `R'  pattern
                     characters are active even if they were substituted for a
                     parameter (regardless of the setting of GLOB_SUBST  which
                     controls  this  feature in normal pattern matching).  The
                     flag `e' can be added to inhibit  pattern  matching.   As
                     this  flag  does not inhibit other forms of substitution,
                     care is still required; using a parameter to hold the key
                     has the desired effect:

                             key2='original key'
                             print ${array[(Re)$key2]}

       i      Like `r', but gives the index of the match instead; this may not
              be combined with a second argument.  On  the  left  side  of  an
              assignment,  behaves  like `r'.  For associative arrays, the key
              part of each pair is compared to  the  pattern,  and  the  first
              matching  key  found  is the result.  On failure substitutes the
              length of the array plus one, as discussed under the description
              of `r', or the empty string for an associative array.

       I      Like `i', but gives the index of the last match, or all possible
              matching keys in an associative array.  On  failure  substitutes
              0,  or  the empty string for an associative array.  This flag is
              best when testing for values or keys that do not exist.

       k      If used in a subscript on an associative array, this flag causes
              the  keys  to  be interpreted as patterns, and returns the value
              for the first key found where exp is matched by the  key.   Note
              this  could be any such key as no ordering of associative arrays
              is defined.  This flag does not work on  the  left  side  of  an
              assignment  to an associative array element.  If used on another
              type of parameter, this behaves like `r'.

       K      On an associative array this is like `k' but returns all  values
              where  exp is matched by the keys.  On other types of parameters
              this has the same effect as `R'.

              If combined with `r', `R', `i' or `I', makes them give  the  nth
              or  nth  last  match  (if  expr  evaluates  to n).  This flag is
              ignored when the array is associative.  The delimiter  character
              : is arbitrary; see above.

              If  combined  with `r', `R', `i' or `I', makes them begin at the
              nth or nth last element, word, or character (if  expr  evaluates
              to n).  This flag is ignored when the array is associative.  The
              delimiter character : is arbitrary; see above.

       e      This flag causes any pattern matching that would be performed on
              the  subscript  to  use  plain  string  matching instead.  Hence
              `${array[(re)*]}' matches only the array element whose value  is
              *.   Note  that  other  forms  of substitution such as parameter
              substitution are not inhibited.

              This flag can also be used to force * or @ to be interpreted  as
              a  single  key rather than as a reference to all values.  It may
              be used for either purpose on the left side of an assignment.

       See Parameter Expansion  Flags  (zshexpn(1))  for  additional  ways  to
       manipulate the results of array subscripting.

   Subscript Parsing
       This  discussion applies mainly to associative array key strings and to
       patterns used for reverse subscripting (the `r', `R', `i', etc. flags),
       but  it  may also affect parameter substitutions that appear as part of
       an arithmetic expression in an ordinary subscript.

       It is possible to  avoid  the  use  of  subscripts  in  assignments  to
       associative array elements by using the syntax:

                 aa+=('key with "*strange*" characters' 'value string')

       This  adds  a new key/value pair if the key is not already present, and
       replaces the value for the existing key if it is.

       The basic rule to remember when writing a subscript expression is  that
       all  text between the opening `[' and the closing `]' is interpreted as
       if it were in double quotes (see zshmisc(1)).  However,  unlike  double
       quotes  which  normally  cannot  nest, subscript expressions may appear
       inside double-quoted strings or inside other subscript expressions  (or
       both!), so the rules have two important differences.

       The  first  difference  is  that  brackets (`[' and `]') must appear as
       balanced pairs in a subscript expression unless they are preceded by  a
       backslash  (`\').  Therefore, within a subscript expression (and unlike
       true double-quoting) the sequence `\[' becomes `[', and similarly  `\]'
       becomes  `]'.   This  applies  even  in  cases where a backslash is not
       normally required; for  example,  the  pattern  `[^[]'  (to  match  any
       character  other  than  an open bracket) should be written `[^\[]' in a
       reverse-subscript pattern.   However,  note  that  `\[^\[\]'  and  even
       `\[^[]'  mean  the  same thing, because backslashes are always stripped
       when they appear before brackets!

       The same rule applies to parentheses (`(' and `)') and braces (`{'  and
       `}'):  they  must  appear  either  in  balanced  pairs or preceded by a
       backslash, and backslashes  that  protect  parentheses  or  braces  are
       removed  during  parsing.   This is because parameter expansions may be
       surrounded by balanced braces, and subscript flags  are  introduced  by
       balanced parentheses.

       The  second  difference is that a double-quote (`"') may appear as part
       of a subscript expression without being preceded by  a  backslash,  and
       therefore  that the two characters `\"' remain as two characters in the
       subscript (in true double-quoting, `\"' becomes `"').  However, because
       of the standard shell quoting rules, any double-quotes that appear must
       occur in balanced pairs unless preceded by a backslash.  This makes  it
       more  difficult  to  write  a subscript expression that contains an odd
       number of double-quote characters, but the reason for  this  difference
       is   so   that   when   a  subscript  expression  appears  inside  true
       double-quotes, one can still write `\"' (rather than `\\\"') for `"'.

       To use an odd number of double quotes as a key in  an  assignment,  use
       the typeset builtin and an enclosing pair of double quotes; to refer to
       the value of that key, again use double quotes:

              typeset -A aa
              typeset "aa[one\"two\"three\"quotes]"=QQQ
              print "$aa[one\"two\"three\"quotes]"

       It is important to note that the quoting rules do  not  change  when  a
       parameter expansion with a subscript is nested inside another subscript
       expression.  That is, it is not necessary to use additional backslashes
       within the inner subscript expression; they are removed only once, from
       the innermost subscript outwards.  Parameters are  also  expanded  from
       the innermost subscript first, as each expansion is encountered left to
       right in the outer expression.

       A further complication arises from a way in which subscript parsing  is
       not  different  from  double quote parsing.  As in true double-quoting,
       the sequences `\*', and `\@' remain as two characters when they  appear
       in  a  subscript  expression.   To  use  a  literal  `*'  or  `@' as an
       associative array key, the `e' flag must be used:

              typeset -A aa
              print $aa[(e)*]

       A  last  detail  must  be  considered  when  reverse  subscripting   is
       performed.   Parameters appearing in the subscript expression are first
       expanded and then the complete expression is interpreted as a  pattern.
       This has two effects: first, parameters behave as if GLOB_SUBST were on
       (and it cannot be turned  off);  second,  backslashes  are  interpreted
       twice, once when parsing the array subscript and again when parsing the
       pattern.   In  a  reverse  subscript,  it's  necessary  to   use   four
       backslashes  to  cause  a  single  backslash  to match literally in the
       pattern.  For complex patterns, it  is  often  easiest  to  assign  the
       desired  pattern to a parameter and then refer to that parameter in the
       subscript, because then the backslashes, brackets,  parentheses,  etc.,
       are  seen  only when the complete expression is converted to a pattern.
       To match the value of a parameter literally  in  a  reverse  subscript,
       rather  than  as  a pattern, use `${(q)name}' (see zshexpn(1)) to quote
       the expanded value.

       Note that the `k'  and  `K'  flags  are  reverse  subscripting  for  an
       ordinary  array,  but  are  not reverse subscripting for an associative
       array!  (For an associative array, the keys in  the  array  itself  are
       interpreted as patterns by those flags; the subscript is a plain string
       in that case.)

       One final note, not directly related to subscripting: the numeric names
       of positional parameters (described below) are parsed specially, so for
       example  `$2foo'  is  equivalent  to  `${2}foo'.   Therefore,  to   use
       subscript  syntax  to  extract a substring from a positional parameter,
       the expansion must be surrounded by braces;  for  example,  `${2[3,5]}'
       evaluates   to  the  third  through  fifth  characters  of  the  second
       positional parameter, but `$2[3,5]'  is  the  entire  second  parameter
       concatenated with the filename generation pattern `[3,5]'.


       The  positional parameters provide access to the command-line arguments
       of a shell function, shell script, or the shell itself; see the section
       `Invocation', and also the section `Functions'.  The parameter n, where
       n is a number, is the nth positional parameter.  The  parameters  *,  @
       and  argv  are  arrays  containing  all the positional parameters; thus
       `$argv[n]', etc., is equivalent to simply `$n'.

       Positional parameters may be changed after the shell or function starts
       by  using the set builtin, by assigning to the argv array, or by direct
       assignment of  the  form  `n=value'  where  n  is  the  number  of  the
       positional  parameter  to  be  changed.   This also creates (with empty
       values) any of the positions from 1 to  n  that  do  not  already  have
       values.  Note that, because the positional parameters form an array, an
       array assignment of the form `n=(value ...)' is allowed,  and  has  the
       effect  of  shifting  all  the values at positions greater than n by as
       many positions as necessary to accommodate the new values.


       Shell  function  executions  delimit  scopes  for   shell   parameters.
       (Parameters  are  dynamically  scoped.)   The  typeset builtin, and its
       alternative  forms  declare,  integer,  local  and  readonly  (but  not
       export),  can  be  used  to  declare  a parameter as being local to the
       innermost scope.

       When a parameter  is  read  or  assigned  to,  the  innermost  existing
       parameter  of  that  name is used.  (That is, the local parameter hides
       any  less-local  parameter.)   However,  assigning  to  a  non-existent
       parameter,  or  declaring  a new parameter with export, causes it to be
       created in the outermost scope.

       Local parameters disappear when their scope ends.  unset can be used to
       delete  a  parameter while it is still in scope; any outer parameter of
       the same name remains hidden.

       Special parameters may also be made local; they  retain  their  special
       attributes  unless  either  the existing or the newly-created parameter
       has the -h (hide) attribute.  This may have unexpected  effects:  there
       is  no  default  value,  so  if there is no assignment at the point the
       variable is made local, it will be set to an empty value  (or  zero  in
       the case of integers).  The following:

              typeset PATH=/new/directory:$PATH

       is  valid  for temporarily allowing the shell or programmes called from
       it to find the programs in /new/directory inside a function.

       Note  that  the  restriction  in  older  versions  of  zsh  that  local
       parameters were never exported has been removed.


       The following parameters are automatically set by the shell:

       ! <S>  The  process  ID  of  the last command started in the background
              with &, or put into the background with the bg builtin.

       # <S>  The number of positional parameters in decimal.  Note that  some
              confusion  may  occur  with the syntax $#param which substitutes
              the length of param.   Use  ${#}  to  resolve  ambiguities.   In
              particular, the sequence `$#-...' in an arithmetic expression is
              interpreted as the length of the parameter -, q.v.

       ARGC <S> <Z>
              Same as #.

       $ <S>  The process ID of this shell.   Note  that  this  indicates  the
              original  shell  started  by  invoking zsh; all processes forked
              from the  shells  without  executing  a  new  program,  such  as
              subshells started by (...), substitute the same value.

       - <S>  Flags  supplied  to  the  shell  on  invocation or by the set or
              setopt commands.

       * <S>  An array containing the positional parameters.

       argv <S> <Z>
              Same as *.  Assigning  to  argv  changes  the  local  positional
              parameters,  but argv is not itself a local parameter.  Deleting
              argv with unset in any function deletes it everywhere,  although
              only  the  innermost positional parameter array is deleted (so *
              and @ in other scopes are not affected).

       @ <S>  Same as argv[@], even when argv is not set.

       ? <S>  The exit status returned by the last command.

       0 <S>  The  name  used  to  invoke   the   current   shell.    If   the
              FUNCTION_ARGZERO option is set, this is set temporarily within a
              shell function to the name of the function, and within a sourced
              script to the name of the script.

       status <S> <Z>
              Same as ?.

       pipestatus <S> <Z>
              An  array  containing the exit statuses returned by all commands
              in the last pipeline.

       _ <S>  The last argument of the previous command.  Also, this parameter
              is  set in the environment of every command executed to the full
              pathname of the command.

              The machine type (microprocessor class  or  machine  model),  as
              determined at run time.

       EGID <S>
              The  effective  group  ID  of  the  shell  process.  If you have
              sufficient privileges, you may change the effective group ID  of
              the   shell  process  by  assigning  to  this  parameter.   Also
              (assuming sufficient privileges), you may start a single command
              with a different effective group ID by `(EGID=gid; command)'

       EUID <S>
              The  effective  user  ID  of  the  shell  process.   If you have
              sufficient privileges, you may change the effective user  ID  of
              the   shell  process  by  assigning  to  this  parameter.   Also
              (assuming sufficient privileges), you may start a single command
              with a different effective user ID by `(EUID=uid; command)'

       ERRNO <S>
              The  value  of  errno (see errno(3)) as set by the most recently
              failed system call.  This  value  is  system  dependent  and  is
              intended  for  debugging  purposes.   It is also useful with the
              zsh/system module which allows the number to be  turned  into  a
              name or message.

       GID <S>
              The  real group ID of the shell process.  If you have sufficient
              privileges, you may change the group ID of the shell process  by
              assigning   to   this   parameter.   Also  (assuming  sufficient
              privileges), you may start a single command  under  a  different
              group ID by `(GID=gid; command)'

              The  current  history  line  number  in an interactive shell, in
              other words the line number for the command that caused $HISTCMD
              to be read.

       HOST   The current hostname.

       LINENO <S>
              The  line  number of the current line within the current script,
              sourced file, or shell function being  executed,  whichever  was
              started most recently.  Note that in the case of shell functions
              the line number refers to the function as  it  appeared  in  the
              original   definition,  not  necessarily  as  displayed  by  the
              functions builtin.

              If the corresponding variable is not set in the  environment  of
              the  shell, it is initialized to the login name corresponding to
              the current login session. This parameter is exported by default
              but this can be disabled using the typeset builtin.

              The  machine  type  (microprocessor  class or machine model), as
              determined at compile time.

       OLDPWD The previous working directory.  This  is  set  when  the  shell
              initializes and whenever the directory changes.

       OPTARG <S>
              The  value  of the last option argument processed by the getopts

       OPTIND <S>
              The index of the last option argument processed by  the  getopts

       OSTYPE The operating system, as determined at compile time.

       PPID <S>
              The process ID of the parent of the shell.  As for $$, the value
              indicates the parent of the original shell and does  not  change
              in subshells.

       PWD    The  present  working  directory.   This  is  set when the shell
              initializes and whenever the directory changes.

       RANDOM <S>
              A pseudo-random integer from 0 to 32767,  newly  generated  each
              time  this parameter is referenced.  The random number generator
              can be seeded by assigning a numeric value to RANDOM.

              The  values   of   RANDOM   form   an   intentionally-repeatable
              pseudo-random  sequence;  subshells  that  reference RANDOM will
              result in identical pseudo-random values  unless  the  value  of
              RANDOM  is  referenced  or seeded in the parent shell in between
              subshell invocations.

       SECONDS <S>
              The number of seconds since shell invocation.  If this parameter
              is assigned a value, then the value returned upon reference will
              be the value that was assigned plus the number of seconds  since
              the assignment.

              Unlike  other  special  parameters,  the  type  of  the  SECONDS
              parameter can  be  changed  using  the  typeset  command.   Only
              integer  and  one  of the floating point types are allowed.  For
              example, `typeset -F SECONDS' causes the value to be reported as
              a  floating point number.  The value is available to microsecond
              accuracy, although the shell  may  show  more  or  fewer  digits
              depending  on the use of typeset.  See the documentation for the
              builtin typeset in zshbuiltins(1) for more details.

       SHLVL <S>
              Incremented by one each time a new shell is started.

              An array containing the names of the signals.

              In an always block, indicates whether the preceding list of code
              caused  an  error.   The  value  is  1  to  indicate an error, 0
              otherwise.  It may be reset, clearing the error condition.   See
              Complex Commands in zshmisc(1)

       TTY    The name of the tty associated with the shell, if any.

       TTYIDLE <S>
              The idle time of the tty associated with the shell in seconds or
              -1 if there is no such tty.

       UID <S>
              The real user ID of the shell process.  If you  have  sufficient
              privileges, you may change the user ID of the shell by assigning
              to this parameter.  Also (assuming sufficient  privileges),  you
              may  start  a  single  command  under  a  different  user  ID by
              `(UID=uid; command)'

       USERNAME <S>
              The username corresponding to the real  user  ID  of  the  shell
              process.   If you have sufficient privileges, you may change the
              username (and also the user ID and group ID)  of  the  shell  by
              assigning   to   this   parameter.   Also  (assuming  sufficient
              privileges), you may start a single command  under  a  different
              username  (and  user  ID  and  group ID) by `(USERNAME=username;

       VENDOR The vendor, as determined at compile time.

              Expands to the basename of  the  command  used  to  invoke  this
              instance of zsh.

              The revision string for the version number of the ChangeLog file
              in the zsh distribution.  This is most useful in order  to  keep
              track  of  versions  of  the  shell  during  development between
              releases; hence most users should not use it and should  instead
              rely on $ZSH_VERSION.

              See the section `The zsh/sched Module' in zshmodules(1).

              Readonly  integer.   Initially  zero,  incremented each time the
              shell forks to create a  subshell  for  executing  code.   Hence
              `(print   $ZSH_SUBSHELL)'  and  `print  $(print  $ZSH_SUBSHELL)'
              output 1, while `( (print $ZSH_SUBSHELL) )' outputs 2.

              The version number of the release of zsh.


       The following parameters are used by the shell.

       In cases where there are two parameters with an  upper-  and  lowercase
       form  of the same name, such as path and PATH, the lowercase form is an
       array and the uppercase form is a scalar with the elements of the array
       joined  together  by  colons.   These  are  similar  to tied parameters
       created via `typeset -T'.  The normal use for the colon-separated  form
       is  for exporting to the environment, while the array form is easier to
       manipulate within the shell.  Note that unsetting either  of  the  pair
       will  unset  the  other;  they  retain  their  special  properties when
       recreated, and recreating one of the pair will recreate the other.

       ARGV0  If exported, its value  is  used  as  the  argv[0]  of  external
              commands.    Usually   used   in  constructs  like  `ARGV0=emacs

       BAUD   The rate in bits per second at which data reaches the  terminal.
              The line editor will use this value in order to compensate for a
              slow  terminal  by  delaying  updates  to  the   display   until
              necessary.   If  the parameter is unset or the value is zero the
              compensation mechanism is turned off.  The parameter is not  set
              by default.

              This parameter may be profitably set in some circumstances, e.g.
              for slow modems dialing into a communications server,  or  on  a
              slow  wide  area  network.  It should be set to the baud rate of
              the slowest part of the link for best performance.

       cdpath <S> <Z> (CDPATH <S>)
              An array (colon-separated list) of  directories  specifying  the
              search path for the cd command.

       COLUMNS <S>
              The  number  of  columns  for  this  terminal session.  Used for
              printing select lists and for the line editor.

              If set, is treated as a pattern during spelling correction.  Any
              potential  correction  that matches the pattern is ignored.  For
              example, if the value is `_*' then completion functions  (which,
              by  convention,  have  names  beginning  with `_') will never be
              offered as spelling corrections.  The pattern does not apply the
              correction  of  file names, as applied by the CORRECT_ALL option
              (so with the example just given files beginning with `_' in  the
              current directory would still be completed).

              The  maximum  size  of  the  directory stack.  If the stack gets
              larger than this, it will be truncated automatically.   This  is
              useful with the AUTO_PUSHD option.

       ENV    If the ENV environment variable is set when zsh is invoked as sh
              or ksh, $ENV is sourced after the profile scripts.  The value of
              ENV  is  subjected to parameter expansion, command substitution,
              and arithmetic expansion before being interpreted as a pathname.
              Note that ENV is not used unless zsh is emulating sh or ksh.

       FCEDIT The  default  editor  for the fc builtin.  If FCEDIT is not set,
              the parameter EDITOR is used; if  that  is  not  set  either,  a
              builtin default, usually vi, is used.

       fignore <S> <Z> (FIGNORE <S>)
              An array (colon separated list) containing the suffixes of files
              to  be  ignored  during  filename   completion.    However,   if
              completion only generates files with suffixes in this list, then
              these files are completed anyway.

       fpath <S> <Z> (FPATH <S>)
              An array (colon separated list) of  directories  specifying  the
              search  path  for  function  definitions.  This path is searched
              when a function with the -u  attribute  is  referenced.   If  an
              executable  file  is  found, then it is read and executed in the
              current environment.

       histchars <S>
              Three  characters  used  by  the  shell's  history  and  lexical
              analysis  mechanism.  The first character signals the start of a
              history expansion (default `!').  The second  character  signals
              the  start  of  a quick history substitution (default `^').  The
              third character is the comment character (default `#').

              The characters must be in the ASCII character set;  any  attempt
              to  set  histchars to characters with a locale-dependent meaning
              will be rejected with an error message.

       HISTCHARS <S> <Z>
              Same as histchars.  (Deprecated.)

              The file to save the history in when an interactive shell exits.
              If unset, the history is not saved.

       HISTSIZE <S>
              The  maximum  number  of  events  stored in the internal history
              list.  If you use  the  HIST_EXPIRE_DUPS_FIRST  option,  setting
              this  value  larger  than  the  SAVEHIST  size will give you the
              difference as a cushion for saving duplicated history events.

       HOME <S>
              The default argument for  the  cd  command.   This  is  not  set
              automatically  by  the shell in sh, ksh or csh emulation, but it
              is typically present  in  the  environment  anyway,  and  if  it
              becomes set it has its usual special behaviour.

       IFS <S>
              Internal  field  separators  (by default space, tab, newline and
              NUL), that are used to separate words which result from  command
              or  parameter expansion and words read by the read builtin.  Any
              characters from the set space, tab and newline  that  appear  in
              the IFS are called IFS white space.  One or more IFS white space
              characters or one non-IFS white space  character  together  with
              any  adjacent  IFS white space character delimit a field.  If an
              IFS white space character appears  twice  consecutively  in  the
              IFS,  this  character  is treated as if it were not an IFS white
              space character.

              If the parameter is unset, the default is used.  Note this has a
              different  effect from setting the parameter to an empty string.

              The time the shell waits, in hundredths of seconds, for  another
              key  to be pressed when reading bound multi-character sequences.

       LANG <S>
              This variable determines the locale category  for  any  category
              not specifically selected via a variable starting with `LC_'.

       LC_ALL <S>
              This variable overrides the value of the `LANG' variable and the
              value of any of the other variables starting with `LC_'.

       LC_COLLATE <S>
              This variable  determines  the  locale  category  for  character
              collation  information  within  ranges  in glob brackets and for

       LC_CTYPE <S>
              This variable  determines  the  locale  category  for  character
              handling  functions.   If the MULTIBYTE option is in effect this
              variable or LANG  should  contain  a  value  that  reflects  the
              character set in use, even if it is a single-byte character set,
              unless only the 7-bit subset (ASCII) is used.  For  example,  if
              the  character  set  is  ISO-8859-1,  a  suitable value might be
              en_US.iso88591 (certain Linux distributions) or  en_US.ISO8859-1

       LC_MESSAGES <S>
              This  variable  determines the language in which messages should
              be written.  Note that zsh does not use message catalogs.

       LC_NUMERIC <S>
              This variable affects the decimal point character and  thousands
              separator character for the formatted input/output functions and
              string conversion functions.  Note that zsh ignores this setting
              when parsing floating point mathematical expressions.

       LC_TIME <S>
              This  variable  determines the locale category for date and time
              formatting in prompt escape sequences.

       LINES <S>
              The number  of  lines  for  this  terminal  session.   Used  for
              printing select lists and for the line editor.

              In the line editor, the number of matches to list without asking
              first. If the value is negative, the list will be  shown  if  it
              spans  at most as many lines as given by the absolute value.  If
              set to zero, the shell asks only if the top of the listing would
              scroll off the screen.

              The interval in seconds between checks for login/logout activity
              using the watch parameter.

       MAIL   If this parameter is set and mailpath  is  not  set,  the  shell
              looks for mail in the specified file.

              The interval in seconds between checks for new mail.

       mailpath <S> <Z> (MAILPATH <S>)
              An  array  (colon-separated  list) of filenames to check for new
              mail.  Each filename can be followed by a `?' and a message that
              will  be printed.  The message will undergo parameter expansion,
              command substitution and arithmetic expansion with the  variable
              $_  defined  as  the  name  of  the  file that has changed.  The
              default message is `You have new mail'.   If  an  element  is  a
              directory  instead  of  a  file the shell will recursively check
              every file in every subdirectory of the element.

       manpath <S> <Z> (MANPATH <S> <Z>)
              An array (colon-separated list) whose value is not used  by  the
              shell.   The manpath array can be useful, however, since setting
              it also sets MANPATH, and vice versa.

       module_path <S> <Z> (MODULE_PATH <S>)
              An array (colon-separated list)  of  directories  that  zmodload
              searches  for dynamically loadable modules.  This is initialized
              to         a         standard         pathname,          usually
              `/usr/local/lib/zsh/$ZSH_VERSION'.   (The  `/usr/local/lib' part
              varies  from  installation  to  installation.)    For   security
              reasons,  any  value  set  in  the environment when the shell is
              started will be ignored.

              These parameters only exist if the installation supports dynamic
              module loading.

       NULLCMD <S>
              The command name to assume if a redirection is specified with no
              command.  Defaults to cat.  For sh/ksh behavior, change this  to
              :.   For csh-like behavior, unset this parameter; the shell will
              print an error message if null commands are entered.

       path <S> <Z> (PATH <S>)
              An array (colon-separated list) of  directories  to  search  for
              commands.  When this parameter is set, each directory is scanned
              and all files found are put in a hash table.

       POSTEDIT <S>
              This string is  output  whenever  the  line  editor  exits.   It
              usually contains termcap strings to reset the terminal.

       PROMPT <S> <Z>
       PROMPT2 <S> <Z>
       PROMPT3 <S> <Z>
       PROMPT4 <S> <Z>
              Same as PS1, PS2, PS3 and PS4, respectively.

       prompt <S> <Z>
              Same as PS1.

              When   the   PROMPT_CR   and  PROMPT_SP  options  are  set,  the
              PROMPT_EOL_MARK parameter can be used to customize how  the  end
              of  partial  lines  are  shown.  This parameter undergoes prompt
              expansion, with the PROMPT_PERCENT option set.  If  not  set  or
              empty,   the   default  behavior  is  equivalent  to  the  value

       PS1 <S>
              The primary prompt string, printed before a command is read.  It
              undergoes  a  special  form of expansion before being displayed;
              see EXPANSION OF PROMPT SEQUENCES in zshmisc(1).  The default is
              `%m%# '.

       PS2 <S>
              The   secondary  prompt,  printed  when  the  shell  needs  more
              information to complete a command.  It is expanded in  the  same
              way  as  PS1.   The  default is `%_> ', which displays any shell
              constructs  or  quotation  marks  which  are   currently   being

       PS3 <S>
              Selection  prompt  used within a select loop.  It is expanded in
              the same way as PS1.  The default is `?# '.

       PS4 <S>
              The execution  trace  prompt.   Default  is  `+%N:%i>  ',  which
              displays  the  name  of the current shell structure and the line
              number within it.  In sh or ksh emulation, the default is `+  '.

       psvar <S> <Z> (PSVAR <S>)
              An  array  (colon-separated list) whose first nine values can be
              used in PROMPT strings.  Setting psvar also sets PSVAR, and vice

              The  command  name  to  assume  if a single input redirection is
              specified with no command.  Defaults to more.

              If  nonnegative,  commands  whose  combined  user   and   system
              execution  times  (measured  in  seconds)  are greater than this
              value have timing statistics printed for them.

       REPLY  This parameter is reserved by convention to pass  string  values
              between  shell  scripts and shell builtins in situations where a
              function call or redirection are impossible or undesirable.  The
              read  builtin  and the select complex command may set REPLY, and
              filename generation  both  sets  and  examines  its  value  when
              evaluating  certain expressions.  Some modules also employ REPLY
              for similar purposes.

       reply  As REPLY, but for array values rather than strings.

       RPROMPT <S>
       RPS1 <S>
              This prompt is displayed on the right-hand side  of  the  screen
              when  the  primary  prompt is being displayed on the left.  This
              does not work  if  the  SINGLELINEZLE  option  is  set.   It  is
              expanded in the same way as PS1.

       RPROMPT2 <S>
       RPS2 <S>
              This  prompt  is  displayed on the right-hand side of the screen
              when the secondary prompt is being displayed on the left.   This
              does  not  work  if  the  SINGLELINEZLE  option  is  set.  It is
              expanded in the same way as PS2.

              The maximum number of history events  to  save  in  the  history

       SPROMPT <S>
              The  prompt  used  for  spelling  correction.  The sequence `%R'
              expands  to  the  string   which   presumably   needs   spelling
              correction,  and  `%r'  expands to the proposed correction.  All
              other prompt escapes are also allowed.

       STTY   If this parameter is set in a command's environment,  the  shell
              runs  the  stty  command  with  the  value  of this parameter as
              arguments in order to set up the terminal before  executing  the
              command. The modes apply only to the command, and are reset when
              it finishes or is suspended. If the  command  is  suspended  and
              continued  later  with  the  fg or wait builtins it will see the
              modes specified by STTY, as if  it  were  not  suspended.   This
              (intentionally)  does  not apply if the command is continued via
              `kill -CONT'.  STTY is ignored if the  command  is  run  in  the
              background,  or if it is in the environment of the shell but not
              explicitly assigned to in the input line.  This  avoids  running
              stty  at  every  external  command by accidentally exporting it.
              Also  note  that  STTY  should  not  be  used  for  window  size
              specifications; these will not be local to the command.

       TERM <S>
              The  type  of  terminal  in  use.   This is used when looking up
              termcap  sequences.   An  assignment  to  TERM  causes  zsh   to
              re-initialize  the  terminal,  even if the value does not change
              (e.g.,  `TERM=$TERM').   It  is  necessary  to  make   such   an
              assignment  upon  any change to the terminal definition database
              or terminal type in order for the new settings to take effect.

              The format of process time reports with the time  keyword.   The
              default is `%E real  %U user  %S system  %P %J'.  Recognizes the
              following escape sequences, although not all may be available on
              all systems, and some that are available may not be useful:

              %%     A `%'.
              %U     CPU seconds spent in user mode.
              %S     CPU seconds spent in kernel mode.
              %E     Elapsed time in seconds.
              %P     The CPU percentage, computed as (100*%U+%S)/%E.
              %W     Number of times the process was swapped.
              %X     The average amount in (shared) text space used in Kbytes.
              %D     The average amount in (unshared) data/stack space used in
              %K     The total space used (%X+%D) in Kbytes.
              %M     The  maximum memory the process had in use at any time in
              %F     The number of  major  page  faults  (page  needed  to  be
                     brought from disk).
              %R     The number of minor page faults.
              %I     The number of input operations.
              %O     The number of output operations.
              %r     The number of socket messages received.
              %s     The number of socket messages sent.
              %k     The number of signals received.
              %w     Number of voluntary context switches (waits).
              %c     Number of involuntary context switches.
              %J     The name of this job.

              A  star  may  be  inserted  between  the  percent sign and flags
              printing  time.   This  cause  the  time  to   be   printed   in
              `hh:mm:ss.ttt'  format  (hours  and  minutes are only printed if
              they are not zero).

       TMOUT  If this parameter is nonzero, the shell  will  receive  an  ALRM
              signal  if  a command is not entered within the specified number
              of seconds after issuing  a  prompt.  If  there  is  a  trap  on
              SIGALRM,  it will be executed and a new alarm is scheduled using
              the value of the TMOUT parameter after executing the  trap.   If
              no  trap  is  set, and the idle time of the terminal is not less
              than  the  value  of  the  TMOUT  parameter,   zsh   terminates.
              Otherwise  a  new  alarm is scheduled to TMOUT seconds after the
              last keypress.

              A pathname prefix which the shell will  use  for  all  temporary
              files.   Note  that  this should include an initial part for the
              file name as well  as  any  directory  names.   The  default  is

       watch <S> <Z> (WATCH <S>)
              An  array  (colon-separated  list)  of  login/logout  events  to
              report.   If  it  contains  the  single  word  `all',  then  all
              login/logout  events  are  reported.   If it contains the single
              word `notme', then all events are reported as with `all'  except
              $USERNAME.   An entry in this list may consist of a username, an
              `@' followed by a remote hostname, and a `%' followed by a  line
              (tty).   Any  or  all  of  these components may be present in an
              entry; if a login/logout  event  matches  all  of  them,  it  is

              The  format  of  login/logout  reports if the watch parameter is
              set.  Default is  `%n  has  %a  %l  from  %m'.   Recognizes  the
              following escape sequences:

              %n     The name of the user that logged in/out.

              %a     The observed action, i.e. "logged on" or "logged off".

              %l     The line (tty) the user is logged in on.

              %M     The full hostname of the remote host.

              %m     The hostname up to the first `.'.  If only the IP address
                     is available or the utmp field contains the  name  of  an
                     X-windows display, the whole name is printed.

                     NOTE:  The  `%m' and `%M' escapes will work only if there
                     is a host  name  field  in  the  utmp  on  your  machine.
                     Otherwise they are treated as ordinary strings.

              %S (%s)
                     Start (stop) standout mode.

              %U (%u)
                     Start (stop) underline mode.

              %B (%b)
                     Start (stop) boldface mode.

              %@     The time, in 12-hour, am/pm format.

              %T     The time, in 24-hour format.

              %w     The date in `day-dd' format.

              %W     The date in `mm/dd/yy' format.

              %D     The date in `yy-mm-dd' format.

                     Specifies  a ternary expression.  The character following
                     the x  is  arbitrary;  the  same  character  is  used  to
                     separate the text for the "true" result from that for the
                     "false"  result.   Both  the  separator  and  the   right
                     parenthesis  may  be  escaped  with a backslash.  Ternary
                     expressions may be nested.

                     The test character x may be any one of `l', `n',  `m'  or
                     `M',  which indicate a `true' result if the corresponding
                     escape sequence would return a non-empty value; or it may
                     be  `a',  which  indicates a `true' result if the watched
                     user has logged in, or `false'  if  he  has  logged  out.
                     Other  characters evaluate to neither true nor false; the
                     entire expression is omitted in this case.

                     If the result is `true', then the true-text is  formatted
                     according  to  the  rules  above  and  printed,  and  the
                     false-text is skipped.   If  `false',  the  true-text  is
                     skipped  and  the  false-text  is  formatted and printed.
                     Either or both of the branches may  be  empty,  but  both
                     separators must be present in any case.

       WORDCHARS <S>
              A  list of non-alphanumeric characters considered part of a word
              by the line editor.

       ZBEEP  If set, this gives a string of characters, which can use all the
              same  codes  as  the bindkey command as described in the zsh/zle
              module entry in  zshmodules(1),  that  will  be  output  to  the
              terminal instead of beeping.  This may have a visible instead of
              an audible effect; for example, the string `\e[?5h\e[?5l'  on  a
              vt100 or xterm will have the effect of flashing reverse video on
              and off (if you usually use reverse video, you  should  use  the
              string  `\e[?5l\e[?5h' instead).  This takes precedence over the
              NOBEEP option.

              The directory to search for shell startup files  (.zshrc,  etc),
              if not $HOME.

              These  parameters  are  used  by  the  line  editor.  In certain
              circumstances suffixes (typically space or slash) added  by  the
              completion  system will be removed automatically, either because
              the next editing command was not  an  insertable  character,  or
              because  the  character was marked as requiring the suffix to be

              These variables can contain the sets  of  characters  that  will
              cause  the  suffix to be removed.  If ZLE_REMOVE_SUFFIX_CHARS is
              set, those characters will cause the suffix to  be  removed;  if
              ZLE_SPACE_SUFFIX_CHARS  is  set, those characters will cause the
              suffix to be removed and replaced by a space.

              If ZLE_REMOVE_SUFFIX_CHARS is not set, the default behaviour  is
              equivalent to:

                     ZLE_REMOVE_SUFFIX_CHARS=$' \t\n;&|'

              If  ZLE_REMOVE_SUFFIX_CHARS  is  set but is empty, no characters
              have this behaviour.  ZLE_SPACE_SUFFIX_CHARS  takes  precedence,
              so that the following:


              causes  the  characters  `&' and `|' to remove the suffix but to
              replace it with a space.

              To  illustrate  the  difference,   suppose   that   the   option
              AUTO_REMOVE_SLASH  is  in  effect and the directory DIR has just
              been completed, with an appended /,  following  which  the  user
              types    `&'.     The    default   result   is   `DIR&'.    With
              ZLE_REMOVE_SUFFIX_CHARS set but without including `&' the result
              is  `DIR/&'.  With ZLE_SPACE_SUFFIX_CHARS set to include `&' the
              result is `DIR &'.

              Note that certain  completions  may  provide  their  own  suffix
              removal  or  replacement  behaviour  which  overrides the values
              described here.  See  the  completion  system  documentation  in