zshexpn - zsh expansion and substitution
DESCRIPTION
The types of expansions performed are
History Expansion
Alias Expansion
Process Substitution
Parameter Expansion
Command Substitution
Arithmetic Expansion
Brace Expansion
Filename Expansion
Filename Generation
Expansion is done in the above specified order in five
steps. The first is history expansion, which is only per
formed in interactive shells. The next step is alias
expansion, which is done right before the command line is
parsed. They are followed by process substitution, param
eter expansion, command substitution, arithmetic expansion
and brace expansion which are performed in one step in
left-to-right fashion. After these expansions, all
unquoted occurrences of the characters `\', `'' and `"'
are removed, and the result is subjected to filename
expansion followed by filename generation.
If the SH_FILE_EXPANSION option is set, the order of
expansion is modified for compatibility with sh and ksh.
Filename expansion is performed immediately after alias
expansion, preceding the set of five expansions mentioned
above.
HISTORY EXPANSION
History expansion allows you to use words from previous
command lines in the command line you are typing. This
simplifies spelling corrections and the repetition of com
plicated commands or arguments. Immediately before execu
tion, each command is saved in the history list, the size
of which is controlled by the HISTSIZE parameter. The one
most recent command is always retained in any case. Each
saved command in the history list is called a history
event and is assigned a number, beginning with 1 (one)
when the shell starts up. The history number that you may
see in your prompt (see the section `Prompt Expansion') is
the number that is to be assigned to the next command.
Overview
A history expansion begins with the first character of the
histchars parameter, which is `!' by default, and may
occur anywhere on the command line; history expansions do
not nest. The `!' can be escaped with `\' or can be
its special meaning. Double quotes will not work for
this. Following this history character is an optional
event designator (see the section `Event Designators') and
then an optional word designator (the section `Word Desig
nators'); if neither of these designators is present, no
history expansion occurs.
Input lines containing history expansions are echoed after
being expanded, but before any other expansions take place
and before the command is executed. It is this expanded
form that is recorded as the history event for later ref
erences.
By default, a history reference with no event designator
refers to the same event as any preceding history refer
ence on that command line; if it is the only history ref
erence in a command, it refers to the previous command.
However, if the option CSH_JUNKIE_HISTORY is set, then
every history reference with no event specification always
refers to the previous command.
For example, `!' is the event designator for the previous
command, so `!!:1' always refers to the first word of the
previous command, and `!!$' always refers to the last word
of the previous command. With CSH_JUNKIE_HISTORY set,
then `!:1' and `!$' function in the same manner as `!!:1'
and `!!$', respectively. Conversely, if CSH_JUNKIE_HIS
TORY is unset, then `!:1' and `!$' refer to the first and
last words, respectively, of the same event referenced by
the nearest other history reference preceding them on the
current command line, or to the previous command if there
is no preceding reference.
The character sequence `^foo^bar' (where `^' is actually
the second character of the histchars parameter) repeats
the last command, replacing the string foo with bar. More
precisely, the sequence `^foo^bar^' is synonymous with
`!!:s^foo^bar^', hence other modifiers (see the section
`Modifiers') may follow the final `^'.
If the shell encounters the character sequence `!"' in
the input, the history mechanism is temporarily disabled
until the current list (see zshmisc(1)) is fully parsed.
The `!"' is removed from the input, and any subsequent `!'
characters have no special significance.
A less convenient but more comprehensible form of command
history support is provided by the fc builtin.
Event Designators
An event designator is a reference to a command-line entry
in the history list. In the list below, remember that the
initial `!' in each item may be changed to another
! Start a history expansion, except when followed by
a blank, newline, `=' or `('. If followed immedi
ately by a word designator (see the section `Word
Designators'), this forms a history reference with
no event designator (see the section `Overview').
!! Refer to the previous command. By itself, this
expansion repeats the previous command.
!n Refer to command-line n.
!-n Refer to the current command-line minus n.
!str Refer to the most recent command starting with str.
!?str[?]
Refer to the most recent command containing str.
The trailing `?' is necessary if this reference is
to be followed by a modifier or followed by any
text that is not to be considered part of str.
!# Refer to the current command line typed in so far.
The line is treated as if it were complete up to
and including the word before the one with the `!#'
reference.
!{...} Insulate a history reference from adjacent charac
ters (if necessary).
Word Designators
A word designator indicates which word or words of a given
command line are to be included in a history reference. A
`:' usually separates the event specification from the
word designator. It may be omitted only if the word des
ignator begins with a `^', `$', `*', `-' or `%'. Word
designators include:
0 The first input word (command).
n The nth argument.
^ The first argument. That is, 1.
$ The last argument.
% The word matched by (the most recent) ?str search.
x-y A range of words; x defaults to 0.
* All the arguments, or a null value if there are
none.
x* Abbreviates `x-$'.
x- Like `x*' but omitting word $.
Note that a `%' word designator works only when used in
one of `!%', `!:%' or `!?str?:%', and only when used after
a !? expansion (possibly in an earlier command). Anything
else results in an error, although the error may not be
Modifiers
After the optional word designator, you can add a sequence
of one or more of the following modifiers, each preceded
by a `:'. These modifiers also work on the result of
filename generation and parameter expansion, except where
noted.
h Remove a trailing pathname component, leaving the
head. This works like `dirname'.
r Remove a filename extension of the form `.xxx',
leaving the root name.
e Remove all but the extension.
t Remove all leading pathname components, leaving the
tail. This works like `basename'.
p Print the new command but do not execute it. Only
works with history expansion.
q Quote the substituted words, escaping further sub
stitutions. Works with history expansion and
parameter expansion, though for parameters it is
only useful if the resulting text is to be re-eval
uated such as by eval.
Q Remove one level of quotes from the substituted
words.
x Like q, but break into words at each blank. Does
not work with parameter expansion.
l Convert the words to all lowercase.
u Convert the words to all uppercase.
s/l/r[/]
Substitute r for l as described below. Unless pre
ceded immediately by a g, with no colon between,
the substitution is done only for the first string
that matches l. For arrays and for filename gener
ation, this applies to each word of the expanded
text.
& Repeat the previous s substitution. Like s, may be
preceded immediately by a g. In parameter expan
sion the & must appear inside braces, and in file
name generation it must be quoted with a backslash.
The s/l/r/ substitution works as follows. The left-hand
side of substitutions are not regular expressions, but
delimiter in place of `/'. A backslash quotes the delim
iter character. The character `&', in the right-hand-side
r, is replaced by the text from the left-hand-side l. The
`&' can be quoted with a backslash. A null l uses the
previous string either from the previous l or from the
contextual scan string s from `!?s'. You can omit the
rightmost delimiter if a newline immediately follows r;
the rightmost `?' in a context scan can similarly be omit
ted. Note the same record of the last l and r is main
tained across all forms of expansion.
The following f, F, w and W modifiers work only with
parameter expansion and filename generation. They are
listed here to provide a single point of reference for all
modifiers.
f Repeats the immediately (without a colon) following
modifier until the resulting word doesn't change
any more.
F:expr:
Like f, but repeats only n times if the expression
expr evaluates to n. Any character can be used
instead of the `:'; if `(', `[', or `{' is used as
the opening delimiter, the closing delimiter should
be ')', `]', or `}', respectively.
w Makes the immediately following modifier work on
each word in the string.
W:sep: Like w but words are considered to be the parts of
the string that are separated by sep. Any character
can be used instead of the `:'; opening parentheses
are handled specially, see above.
PROCESS SUBSTITUTION
Each command argument of the form `<(list)', `>(list)' or
`=(list)' is subject to process substitution. In the case
of the < or > forms, the shell runs process list asyn
chronously. If the system supports the /dev/fd mechanism,
the command argument is the name of the device file corre
sponding to a file descriptor; otherwise, if the system
supports named pipes (FIFOs), the command argument will be
a named pipe. If the form with > is selected then writing
on this special file will provide input for list. If < is
used, then the file passed as an argument will be con
nected to the output of the list process. For example,
paste <(cut -f1 file1) <(cut -f3 file2) |
tee >(process1) >(process2) >/dev/null
cuts fields 1 and 3 from the files file1 and file2 respec
tively, pastes the results together, and sends it to the
Both the /dev/fd and the named pipe implementation have
drawbacks. In the former case, some programmes may auto
matically close the file descriptor in question before
examining the file on the command line, particularly if
this is necessary for security reasons such as when the
programme is running setuid. In the second case, if the
programme does not actually open the file the subshell
attempting to read from or write to the pipe will (in a
typical implementation, different operating systems may
have different behaviour) block for ever and have to be
killed explicitly. In both cases, the shell actually sup
plies the information using a pipe, so that programmes
that expect to lseek (see lseek(2)) on the file will not
work.
Also note that the previous example can be more compactly
and efficiently written (provided the MULTIOS option is
set) as:
paste <(cut -f1 file1) <(cut -f3 file2) > >(process1) > >(process2)
The shell uses pipes instead of FIFOs to implement the
latter two process substitutions in the above example.
If = is used, then the file passed as an argument will be
the name of a temporary file containing the output of the
list process. This may be used instead of the < form for
a program that expects to lseek (see lseek(2)) on the
input file.
PARAMETER EXPANSION
The character `$' is used to introduce parameter expan
sions. See zshparam(1) for a description of parameters,
including arrays, associative arrays, and subscript nota
tion to access individual array elements.
In the expansions discussed below that require a pattern,
the form of the pattern is the same as that used for file
name generation; see the section `Filename Generation'.
Note that these patterns, along with the replacement text
of any substitutions, are themselves subject to parameter
expansion, command substitution, and arithmetic expansion.
In addition to the following operations, the file modi
fiers described in the section `Modifiers' in the section
`History Expansion' can be applied: for example,
${i:s/foo/bar/} performs string substitution on the expan
sion of parameter $i.
${name}
The value, if any, of the parameter name is substi
tuted. The braces are required if the expansion is
to be followed by a letter, digit, or underscore
addition, more complicated forms of substitution
usually require the braces to be present; excep
tions, which only apply if the option KSH_ARRAYS is
not set, are a single subscript or any colon modi
fiers appearing after the name, or any of the char
acters `^', `=', `~', `#' or `+' appearing before
the name, all of which work with or without braces.
If name is an array parameter, and the KSH_ARRAYS
option is not set, then the value of each element
of name is substituted, one element per word. Oth
erwise, the expansion results in one word only;
with KSH_ARRAYS, this is the first element of an
array. No field splitting is done on the result
unless the SH_WORD_SPLIT option is set.
${+name}
If name is the name of a set parameter `1' is sub
stituted, otherwise `0' is substituted.
${name:-word}
If name is set and is non-null then substitute its
value; otherwise substitute word. If name is miss
ing, substitute word.
${name:=word}
${name::=word}
In the first form, if name is unset or is null then
set it to word; in the second form, unconditionally
set name to word. In both forms, the value of the
parameter is then substituted.
${name:?word}
If name is set and is non-null then substitute its
value; otherwise, print word and exit from the
shell. Interactive shells instead return to the
prompt. If word is omitted, then a standard mes
sage is printed.
${name:+word}
If name is set and is non-null then substitute
word; otherwise substitute nothing.
If the colon is omitted from one of the above expressions
containing a colon, then the shell only checks whether
name is set, not whether its value is null.
In the following expressions, when name is an array and
the substitution is not quoted, or if the `(@)' flag or
the name[@] syntax is used, matching and replacement is
performed on each array element separately.
${name##pattern}
If the pattern matches the beginning of the value
of name, then substitute the value of name with the
matched portion deleted; otherwise, just substitute
the value of name. In the first form, the smallest
matching pattern is preferred; in the second form,
the largest matching pattern is preferred.
${name%pattern}
${name%%pattern}
If the pattern matches the end of the value of
name, then substitute the value of name with the
matched portion deleted; otherwise, just substitute
the value of name. In the first form, the smallest
matching pattern is preferred; in the second form,
the largest matching pattern is preferred.
${name:#pattern}
If the pattern matches the value of name, then sub
stitute the empty string; otherwise, just substi
tute the value of name. If name is an array the
matching array elements are removed (use the `(M)'
flag to remove the non-matched elements).
${name/pattern/repl}
${name//pattern/repl}
Replace the longest possible match of pattern in
the expansion of parameter name by string repl.
The first form replaces just the first occurrence,
the second form all occurrences. Both pattern and
repl are subject to double-quoted substitution, so
that expressions like ${name/$opat/$npat} will
work, but note the usual rule that pattern charac
ters in $opat are not treated specially unless
either the option GLOB_SUBST is set, or $opat is
instead substituted as ${~opat}.
The pattern may begin with a `#', in which case the
pattern must match at the start of the string, or
`%', in which case it must match at the end of the
string. The repl may be an empty string, in which
case the final `/' may also be omitted. To quote
the final `/' in other cases it should be preceded
by two backslashes (i.e., a quoted backslash); this
is not necessary if the `/' occurs inside a substi
tuted parameter. Note also that the `#' and `%'
are not active if they occur inside a substituted
parameter, even at the start.
The first `/' may be preceded by a `:', in which
case the match will only succeed if it matches the
entire word. Note also the effect of the I and S
parameter expansion flags below; however, the flags
For example,
foo="twinkle twinkle little star" sub="t*e" rep="spy"
print ${foo//${~sub}/$rep}
print ${(S)foo//${~sub}/$rep}
Here, the `~' ensures that the text of $sub is
treated as a pattern rather than a plain string.
In the first case, the longest match for t*e is
substituted and the result is `spy star', while in
the second case, the shortest matches are taken and
the result is `spy spy lispy star'.
${#spec}
If spec is one of the above substitutions, substi
tute the length in characters of the result instead
of the result itself. If spec is an array expres
sion, substitute the number of elements of the
result. Note that `^', `=', and `~', below, must
appear to the left of `#' when these forms are com
bined.
${^spec}
Turn on the RC_EXPAND_PARAM option for the evalua
tion of spec; if the `^' is doubled, turn it off.
When this option is set, array expansions of the
form foo${xx}bar, where the parameter xx is set to
(a b c), are substituted with `fooabar foobbar
foocbar' instead of the default `fooa b cbar'.
Internally, each such expansion is converted into
the equivalent list for brace expansion. E.g.,
${^var} becomes {$var[1],$var[2],...}, and is pro
cessed as described in the section `Brace Expan
sion' below. If word splitting is also in effect
the $var[N] may themselves be split into different
list elements.
${=spec}
Perform word splitting using the rules for
SH_WORD_SPLIT during the evaluation of spec, but
regardless of whether the parameter appears in dou
ble quotes; if the `=' is doubled, turn it off.
This forces parameter expansions to be split into
separate words before substitution, using IFS as a
delimiter. This is done by default in most other
shells.
Note that splitting is applied to word in the
assignment forms of spec before the assignment to
name is performed. This affects the result of
array assignments with the A flag.
Turn on the GLOB_SUBST option for the evaluation of
spec; if the `~' is doubled, turn it off. When
this option is set, the string resulting from the
expansion will be interpreted as a pattern anywhere
that is possible, such as in filename expansion and
filename generation and pattern-matching contexts
like the right hand side of the `=' and `!=' opera
tors in conditions.
If a ${...} type parameter expression or a $(...) type
command substitution is used in place of name above, it is
expanded first and the result is used as if it were the
value of name. Thus it is possible to perform nested
operations: ${${foo#head}%tail} substitutes the value of
$foo with both `head' and `tail' deleted. The form with
$(...) is often useful in combination with the flags
described next; see the examples below. Each name or
nested ${...} in a parameter expansion may also be fol
lowed by a subscript expression as described in Array
Parameters in zshparam(1).
Note that double quotes may appear around nested expres
sions, in which case only the part inside is treated as
quoted; for example, ${(f)"$(foo)"} quotes the result of
$(foo), but the flag `(f)' (see below) is applied using
the rules for unquoted expansions. Note further that
quotes are themselves nested in this context; for example,
in "${(@f)"$(foo)"}", there are two sets of quotes, one
surrounding the whole expression, the other (redundant)
surrounding the $(foo) as before.
Parameter Expansion Flags
If the opening brace is directly followed by an opening
parenthesis, the string up to the matching closing paren
thesis will be taken as a list of flags. Where arguments
are valid, any character, or the matching pairs `(...)',
`{...}', `[...]', or `<...>', may be used in place of the
colon as delimiters. The following flags are supported:
A Create an array parameter with `${...=...}',
`${...:=...}' or `${...::=...}'. If this flag is
repeated (as in `AA'), create an associative array
parameter. Assignment is made before sorting or
padding. The name part may be a subscripted range
for ordinary arrays; the word part must be con
verted to an array, for example by using
`${(AA)=name=...}' to activate word splitting, when
creating an associative array.
@ In double quotes, array elements are put into sepa
rate words. E.g., `"${(@)foo}"' is equivalent to
`"${foo[@]}"' and `"${(@)foo[1,2]}"' is the same as
e Perform parameter expansion, command substitution
and arithmetic expansion on the result. Such expan
sions can be nested but too deep recursion may have
unpredictable effects.
P This forces the value of the parameter name to be
interpreted as a further parameter name, whose
value will be used where appropriate. If used with
a nested parameter or command substitution, the
result of that will be taken as a parameter name in
the same way. For example, if you have `foo=bar'
and `bar=baz', the strings ${(P)foo}, ${(P)${foo}},
and ${(P)$(echo bar)} will be expanded to `baz'.
o Sort the resulting words in ascending order.
O Sort the resulting words in descending order.
i With o or O, sort case-independently.
L Convert all letters in the result to lower case.
U Convert all letters in the result to upper case.
C Capitalize the resulting words. `Words' in this
case refers to sequences of alphanumeric characters
separated by non-alphanumerics, not to words that
result from field splitting.
V Make any special characters in the resulting words
visible.
q Quote the resulting words with backslashes. If this
flag is given twice, the resulting words are quoted
in single quotes and if it is given three times,
the words are quoted in double quotes. If it is
given four times, the words are quoted in single
quotes preceded by a $.
Q Remove one level of quotes from the resulting
words.
% Expand all % escapes in the resulting words in the
same way as in prompts (see the section `Prompt
Expansion'). If this flag is given twice, full
prompt expansion is done on the resulting words,
depending on the setting of the PROMPT_PERCENT,
PROMPT_SUBST and PROMPT_BANG options.
X With this flag parsing errors occurring with the Q
and e flags or the pattern matching forms such as
`${name#pattern}' are reported. Without the flag
c With ${#name}, count the total number of characters
in an array, as if the elements were concatenated
with spaces between them.
w With ${#name}, count words in arrays or strings;
the s flag may be used to set a word delimiter.
W Similar to w with the difference that empty words
between repeated delimiters are also counted.
k If name refers to an associative array, substitute
the keys (element names) rather than the values of
the elements. Used with subscripts (including
ordinary arrays), force indices or keys to be sub
stituted even if the subscript form refers to val
ues. However, this flag may not be combined with
subscript ranges.
v Used with k, substitute (as two consecutive words)
both the key and the value of each associative
array element. Used with subscripts, force values
to be substituted even if the subscript form refers
to indices or keys.
p Recognize the same escape sequences as the print
builtin in string arguments to any of the flags
described below.
l:expr::string1::string2:
Pad the resulting words on the left. Each word
will be truncated if required and placed in a field
expr characters wide. The space to the left will
be filled with string1 (concatenated as often as
needed) or spaces if string1 is not given. If both
string1 and string2 are given, this string is
inserted once directly to the left of each word,
before padding.
r:expr::string1::string2:
As l, but pad the words on the right and insert
string2 on the right.
j:string:
Join the words of arrays together using string as a
separator. Note that this occurs before field
splitting by the SH_WORD_SPLIT option.
F Join the words of arrays together using newline as
a separator. This is a shorthand for `pj:\n:'.
s:string:
Force field splitting (see the option
only occurs in places where an array value is
valid.
f Split the result of the expansion to lines. This is
a shorthand for `ps:\n:'.
z Split the result of the expansion into words using
shell parsing to find the words, i.e. taking into
account any quoting in the value.
Note that this is done very late, as for the `(s)'
flag. So to access single words in the result, one
has to use nested expansions as in
`${${(z)foo}[2]}'. Likewise, to remove the quotes
in the resulting words one would do:
`${(Q)${(z)foo}}'.
t Use a string describing the type of the parameter
where the value of the parameter would usually
appear. This string consists of keywords separated
by hyphens (`-'). The first keyword in the string
describes the main type, it can be one of `scalar',
`array', `integer', `float' or `association'. The
other keywords describe the type in more detail:
local for local parameters
left for left justified parameters
right_blanks
for right justified parameters with leading
blanks
right_zeros
for right justified parameters with leading
zeros
lower for parameters whose value is converted to
all lower case when it is expanded
upper for parameters whose value is converted to
all upper case when it is expanded
readonly
for readonly parameters
tag for tagged parameters
export for exported parameters
unique for arrays which keep only the first occur
rence of duplicated values
special
for special parameters defined by the shell
The following flags are meaningful with the ${...#...} or
${...%...} forms. The S and I flags may also be used with
the ${.../...} forms.
S Search substrings as well as beginnings or ends;
with # start from the beginning and with % start
from the end of the string. With substitution via
${.../...} or ${...//...}, specifies that the
shortest instead of the longest match should be
replaced.
I:expr:
Search the exprth match (where expr evaluates to a
number). This only applies when searching for sub
strings, either with the S flag, or with ${.../...}
(only the exprth match is substituted) or
${...//...} (all matches from the exprth on are
substituted). The exprth match is counted such
that there is either one or zero matches from each
starting position in the string, although for
global substitution matches overlapping previous
replacements are ignored.
M Include the matched portion in the result.
R Include the unmatched portion in the result (the
Rest).
B Include the index of the beginning of the match in
the result.
E Include the index of the end of the match in the
result.
N Include the length of the match in the result.
Rules
Here is a summary of the rules for substitution; this
assumes that braces are present around the substitution,
i.e. ${...}. Some particular examples are given below.
Note that the Zsh Development Group accepts no responsi
bility for any brain damage which may occur during the
reading of the following rules.
1. Nested Substitution
If multiple nested ${...} forms are present, sub
stitution is performed from the inside outwards.
At each level, the substitution takes account of
whether the whole substitution is in double quotes,
and what flags are supplied to the current level of
substitution, just as if the nested substitution
were the outermost. The flags are not propagated
up to enclosing substitutions; the nested substitu
tion will return either a scalar or an array as
determined by the flags, possibly adjusted for
quoting. All the following steps take place where
applicable at all levels of substitution. Note
that, unless the `(P)' flag is present, the flags
and any subscripts apply directly to the value of
the nested substitution; for example, the expansion
${${foo}} behaves exactly the same as ${foo}.
2. Parameter Subscripting
If the value is a raw parameter reference with a
subscript, such as ${var[3]}, the effect of sub
scripting is applied directly to the parameter.
Subscripts are evaluated left to right; subsequent
subscripts apply to the scalar or array value
yielded by the previous subscript. Thus if var is
an array, ${var[1][2]} is the second character of
the first word, but ${var[2,4][2]} is the entire
third word (the second word of the range of words
two through four of the original array). Any num
ber of subscripts may appear.
3. Parameter Name Replacement
The effect of any (P) flag, which treats the value
so far as a parameter name and replaces it with the
corresponding value, is applied.
4. Double-Quoted Joining
If the value after this process is an array, and
the substitution appears in double quotes, and no
(@) flag is present at the current level, the words
of the value are joined with the first character of
the parameter $IFS, by default a space, between
each word (single word arrays are not modified).
If the (j) flag is present, that is used for join
ing instead of $IFS.
5. Nested Subscripting
Any remaining subscripts (i.e. of a nested substi
tution) are evaluated at this point, based on
whether the value is an array or a scalar. As with
2., multiple subscripts can appear. Note that
${foo[2,4][2]} is thus equivalent to
${${foo[2,4]}[2]} and also to
"${${(@)foo[2,4]}[2]}" (the nested substitution
returns an array in both cases), but not to
"${${foo[2,4]}[2]}" (the nested substitution
returns a scalar because of the quotes).
Any modifiers, as specified by a trailing `#', `%',
`/' (possibly doubled) or by a set of modifiers of
the form :... (see the section `Modifiers' in the
section `History Expansion'), are applied to the
words of the value at this level.
7. Forced Joining
If the `(j)' flag is present, or no `(j)' flag is
present but the string is to be split as given by
rules 8. or 9., and joining did not take place at
step 4., any words in the value are joined together
using the given string or the first character of
$IFS if none. Note that the `(F)' flag implicitly
supplies a string for joining in this manner.
8. Forced Splitting
If one of the `(s)', `(f)' or `(z)' flags are pre
sent, or the `=' specifier was present (e.g.
${=var}), the word is split on occurrences of the
specified string, or (for = with neither of the two
flags present) any of the characters in $IFS.
9. Shell Word Splitting
If no `(s)', `(f)' or `=' was given, but the word
is not quoted and the option SH_WORD_SPLIT is set,
the word is split on occurrences of any of the
characters in $IFS. Note this step, too, takes
place at all levels of a nested substitution.
10. Re-Evaluation
Any `(e)' flag is applied to the value, forcing it
to be re-examined for new parameter substitutions,
but also for command and arithmetic substitutions.
11. Padding
Any padding of the value by the `(l.fill.)' or
`(r.fill.)' flags is applied.
Examples
The flag f is useful to split a double-quoted substitution
line by line. For example, ${(f)"$(<file)"} substitutes
the contents of file divided so that each line is an ele
ment of the resulting array. Compare this with the effect
of $(<file) alone, which divides the file up by words, or
the same inside double quotes, which makes the entire con
tent of the file a single string.
The following illustrates the rules for nested parameter
expansions. Suppose that $foo contains the array (bar
baz):
This produces the result b. First, the inner sub
stitution "${foo}", which has no array (@) flag,
produces a single word result "bar baz". The outer
substitution "${(@)...[1]}" detects that this is a
scalar, so that (despite the `(@)' flag) the sub
script picks the first character.
"${${(@)foo}[1]}"
This produces the result `bar'. In this case, the
inner substitution "${(@)foo}" produces the array
`(bar baz)'. The outer substitution "${...[1]}"
detects that this is an array and picks the first
word. This is similar to the simple case
"${foo[1]}".
As an example of the rules for word splitting and joining,
suppose $foo contains the array `(ax1 bx1)'. Then
${(s/x/)foo}
produces the words `a', `1 b' and `1'.
${(j/x/s/x/)foo}
produces `a', `1', `b' and `1'.
${(s/x/)foo%%1*}
produces `a' and ` b' (note the extra space). As
substitution occurs before either joining or split
ting, the operation first generates the modified
array (ax bx), which is joined to give "ax bx", and
then split to give `a', ` b' and `'. The final
empty string will then be elided, as it is not in
double quotes.
COMMAND SUBSTITUTION
A command enclosed in parentheses preceded by a dollar
sign, like `$(...)', or quoted with grave accents, like
``...`', is replaced with its standard output, with any
trailing newlines deleted. If the substitution is not
enclosed in double quotes, the output is broken into words
using the IFS parameter. The substitution `$(cat foo)'
may be replaced by the equivalent but faster `$(<foo)'.
In either case, if the option GLOB_SUBST is set, the out
put is eligible for filename generation.
ARITHMETIC EXPANSION
A string of the form `$[exp]' or `$((exp))' is substituted
with the value of the arithmetic expression exp. exp is
subjected to parameter expansion, command substitution and
arithmetic expansion before it is evaluated. See the sec
tion `Arithmetic Evaluation'.
A string of the form `foo{xx,yy,zz}bar' is expanded to the
individual words `fooxxbar', `fooyybar' and `foozzbar'.
Left-to-right order is preserved. This construct may be
nested. Commas may be quoted in order to include them
literally in a word.
An expression of the form `{n1..n2}', where n1 and n2 are
integers, is expanded to every number between n1 and n2
inclusive. If either number begins with a zero, all the
resulting numbers will be padded with leading zeroes to
that minimum width. If the numbers are in decreasing
order the resulting sequence will also be in decreasing
order.
If a brace expression matches none of the above forms, it
is left unchanged, unless the BRACE_CCL option is set. In
that case, it is expanded to a sorted list of the individ
ual characters between the braces, in the manner of a
search set. `-' is treated specially as in a search set,
but `^' or `!' as the first character is treated normally.
Note that brace expansion is not part of filename genera
tion (globbing); an expression such as */{foo,bar} is
split into two separate words */foo and */bar before file
name generation takes place. In particular, note that
this is liable to produce a `no match' error if either of
the two expressions does not match; this is to be con
trasted with */(foo|bar), which is treated as a single
pattern but otherwise has similar effects.
FILENAME EXPANSION
Each word is checked to see if it begins with an unquoted
`~'. If it does, then the word up to a `/', or the end of
the word if there is no `/', is checked to see if it can
be substituted in one of the ways described here. If so,
then the `~' and the checked portion are replaced with the
appropriate substitute value.
A `~' by itself is replaced by the value of $HOME. A `~'
followed by a `+' or a `-' is replaced by the value of
$PWD or $OLDPWD, respectively.
A `~' followed by a number is replaced by the directory at
that position in the directory stack. `~0' is equivalent
to `~+', and `~1' is the top of the stack. `~+' followed
by a number is replaced by the directory at that position
in the directory stack. `~+0' is equivalent to `~+', and
`~+1' is the top of the stack. `~-' followed by a number
is replaced by the directory that many positions from the
bottom of the stack. `~-0' is the bottom of the stack.
The PUSHD_MINUS option exchanges the effects of `~+' and
`~-' where they are followed by a number.
up as a named directory, and replaced by the value of that
named directory if found. Named directories are typically
home directories for users on the system. They may also
be defined if the text after the `~' is the name of a
string shell parameter whose value begins with a `/'. It
is also possible to define directory names using the -d
option to the hash builtin.
In certain circumstances (in prompts, for instance), when
the shell prints a path, the path is checked to see if it
has a named directory as its prefix. If so, then the pre
fix portion is replaced with a `~' followed by the name of
the directory. The shortest way of referring to the
directory is used, with ties broken in favour of using a
named directory, except when the directory is / itself.
The parameters $PWD and $OLDPWD are never abbreviated in
this fashion.
If a word begins with an unquoted `=' and the EQUALS
option is set, the remainder of the word is taken as the
name of a command or alias. If a command exists by that
name, the word is replaced by the full pathname of the
command. If an alias exists by that name, the word is
replaced with the text of the alias.
Filename expansion is performed on the right hand side of
a parameter assignment, including those appearing after
commands of the typeset family. In this case, the right
hand side will be treated as a colon-separated list in the
manner of the PATH parameter, so that a `~' or an `=' fol
lowing a `:' is eligible for expansion. All such
behaviour can be disabled by quoting the `~', the `=', or
the whole expression (but not simply the colon); the
EQUALS option is also respected.
If the option MAGIC_EQUAL_SUBST is set, any unquoted shell
argument in the form `identifier=expression' becomes eli
gible for file expansion as described in the previous
paragraph. Quoting the first `=' also inhibits this.
FILENAME GENERATION
If a word contains an unquoted instance of one of the
characters `*', `(', `|', `<', `[', or `?', it is regarded
as a pattern for filename generation, unless the GLOB
option is unset. If the EXTENDED_GLOB option is set, the
`^' and `#' characters also denote a pattern; otherwise
they are not treated specially by the shell.
The word is replaced with a list of sorted filenames that
match the pattern. If no matching pattern is found, the
shell gives an error message, unless the NULL_GLOB option
is set, in which case the word is deleted; or unless the
NOMATCH option is unset, in which case the word is left
In filename generation, the character `/' must be matched
explicitly; also, a `.' must be matched explicitly at the
beginning of a pattern or after a `/', unless the
GLOB_DOTS option is set. No filename generation pattern
matches the files `.' or `..'. In other instances of pat
tern matching, the `/' and `.' are not treated specially.
Glob Operators
* Matches any string, including the null string.
? Matches any character.
[...] Matches any of the enclosed characters. Ranges of
characters can be specified by separating two char
acters by a `-'. A `-' or `]' may be matched by
including it as the first character in the list.
There are also several named classes of characters,
in the form `[:name:]' with the following meanings:
`[:alnum:]' alphanumeric, `[:alpha:]' alphabetic,
`[:blank:]' space or tab, `[:cntrl:]' control char
acter, `[:digit:]' decimal digit, `[:graph:]'
printable character except whitespace, `[:lower:]'
lowercase letter, `[:print:]' printable character,
`[:punct:]' printable character neither alphanu
meric nor whitespace, `[:space:]' whitespace char
acter, `[:upper:]' uppercase letter, `[:xdigit:]'
hexadecimal digit. These use the macros provided
by the operating system to test for the given char
acter combinations, including any modifications due
to local language settings: see ctype(3). Note
that the square brackets are additional to those
enclosing the whole set of characters, so to test
for a single alphanumeric character you need
`[[:alnum:]]'. Named character sets can be used
alongside other types, e.g. `[[:alpha:]0-9]'.
[^...]
[!...] Like [...], except that it matches any character
which is not in the given set.
<[x]-[y]>
Matches any number in the range x to y, inclusive.
Either of the numbers may be omitted to make the
range open-ended; hence `<->' matches any number.
To match individual digits, the [...] form is more
efficient.
Be careful when using other wildcards adjacent to
patterns of this form; for example, <0-9>* will
actually match any number whatsoever at the start
of the string, since the `<0-9>' will match the
first digit, and the `*' will match any others.
inevitable consequence of the rule that the longest
possible match always succeeds. Expressions such
as `<0-9>[^[:digit:]]*' can be used instead.
(...) Matches the enclosed pattern. This is used for
grouping. If the KSH_GLOB option is set, then a
`@', `*', `+', `?' or `!' immediately preceding the
`(' is treated specially, as detailed below. The
option SH_GLOB prevents bare parentheses from being
used in this way, though the KSH_GLOB option is
still available.
Note that grouping cannot extend over multiple
directories: it is an error to have a `/' within a
group (this only applies for patterns used in file
name generation). There is one exception: a group
of the form (pat/)# appearing as a complete path
segment can match a sequence of directories. For
example, foo/(a*/)#bar matches foo/bar,
foo/any/bar, foo/any/anyother/bar, and so on.
x|y Matches either x or y. This operator has lower
precedence than any other. The `|' character must
be within parentheses, to avoid interpretation as a
pipeline.
^x (Requires EXTENDED_GLOB to be set.) Matches any
thing except the pattern x. This has a higher
precedence than `/', so `^foo/bar' will search
directories in `.' except `./foo' for a file named
`bar'.
x~y (Requires EXTENDED_GLOB to be set.) Match anything
that matches the pattern x but does not match y.
This has lower precedence than any operator except
`|', so `*/*~foo/bar' will search for all files in
all directories in `.' and then exclude `foo/bar'
if there was such a match. Multiple patterns can
be excluded by `foo~bar~baz'. In the exclusion
pattern (y), `/' and `.' are not treated specially
the way they usually are in globbing.
x# (Requires EXTENDED_GLOB to be set.) Matches zero
or more occurrences of the pattern x. This opera
tor has high precedence; `12#' is equivalent to
`1(2#)', rather than `(12)#'. It is an error for
an unquoted `#' to follow something which cannot be
repeated; this includes an empty string, a pattern
already followed by `##', or parentheses when part
of a KSH_GLOB pattern (for example, `!(foo)#' is
invalid and must be replaced by `*(!(foo))').
x## (Requires EXTENDED_GLOB to be set.) Matches one or
has high precedence; `12##' is equivalent to
`1(2##)', rather than `(12)##'. No more than two
active `#' characters may appear together.
ksh-like Glob Operators
If the KSH_GLOB option is set, the effects of parentheses
can be modified by a preceding `@', `*', `+', `?' or `!'.
This character need not be unquoted to have special
effects, but the `(' must be.
@(...) Match the pattern in the parentheses. (Like
`(...)'.)
*(...) Match any number of occurrences. (Like `(...)#'.)
+(...) Match at least one occurrence. (Like `(...)##'.)
?(...) Match zero or one occurrence. (Like `(|...)'.)
!(...) Match anything but the expression in parentheses.
(Like `(^(...))'.)
Precedence
The precedence of the operators given above is (highest)
`^', `/', `~', `|' (lowest); the remaining operators are
simply treated from left to right as part of a string,
with `#' and `##' applying to the shortest possible pre
ceding unit (i.e. a character, `?', `[...]', `<...>', or a
parenthesised expression). As mentioned above, a `/' used
as a directory separator may not appear inside parenthe
ses, while a `|' must do so; in patterns used in other
contexts than filename generation (for example, in case
statements and tests within `[[...]]'), a `/' is not spe
cial; and `/' is also not special after a `~' appearing
outside parentheses in a filename pattern.
Globbing Flags
There are various flags which affect any text to their
right up to the end of the enclosing group or to the end
of the pattern; they require the EXTENDED_GLOB option. All
take the form (#X) where X may have one of the following
forms:
i Case insensitive: upper or lower case characters
in the pattern match upper or lower case charac
ters.
l Lower case characters in the pattern match upper or
lower case characters; upper case characters in the
pattern still only match upper case characters.
I Case sensitive: locally negates the effect of i or
l from that point on.
the pattern; this does not work in filename genera
tion. When a pattern with a set of active paren
theses is matched, the strings matched by the
groups are stored in the array $match, the indices
of the beginning of the matched parentheses in the
array $mbegin, and the indices of the end in the
array $mend, with the first element of each array
corresponding to the first parenthesised group, and
so on. These arrays are not otherwise special to
the shell. The indices use the same convention as
does parameter substitution, so that elements of
$mend and $mbegin may be used in subscripts; the
KSH_ARRAYS option is respected. Sets of globbing
flags are not considered parenthesised groups; only
the first nine active parentheses can be refer
enced.
For example,
foo="a string with a message"
if [[ $foo = (a|an)' '(#b)(*)' '* ]]; then
print ${foo[$mbegin[1],$mend[1]]}
fi
prints `string with a'. Note that the first paren
thesis is before the (#b) and does not create a
backreference.
Backreferences work with all forms of pattern
matching other than filename generation, but note
that when performing matches on an entire array,
such as ${array#pattern}, or a global substitution,
such as ${param//pat/repl}, only the data for the
last match remains available. In the case of
global replacements this may still be useful. See
the example for the m flag below.
The numbering of backreferences strictly follows
the order of the opening parentheses from left to
right in the pattern string, although sets of
parentheses may be nested. There are special rules
for parentheses followed by `#' or `##'. Only the
last match of the parenthesis is remembered: for
example, in `[[ abab = (#b)([ab])# ]]', only the
final `b' is stored in match[1]. Thus extra paren
theses may be necessary to match the complete seg
ment: for example, use `X((ab|cd)#)Y' to match a
whole string of either `ab' or `cd' between `X' and
`Y', using the value of $match[1] rather than
$match[2].
If the match fails none of the parameters is
altered, so in some cases it may be necessary to
references fail to match --- which happens if they
are in an alternate branch which fails to match, or
if they are followed by # and matched zero times
--- then the matched string is set to the empty
string, and the start and end indices are set to
-1.
Pattern matching with backreferences is slightly
slower than without.
B Deactivate backreferences, negating the effect of
the b flag from that point on.
m Set references to the match data for the entire
string matched; this is similar to backreferencing
and does not work in filename generation. The flag
must be in effect at the end of the pattern, i.e.
not local to a group. The parameters $MATCH, $MBE
GIN and $MEND will be set to the string matched and
to the indices of the beginning and end of the
string, respectively. This is most useful in
parameter substitutions, as otherwise the string
matched is obvious.
For example,
arr=(veldt jynx grimps waqf zho buck)
print ${arr//(#m)[aeiou]/${(U)MATCH}}
forces all the matches (i.e. all vowels) into
uppercase, printing `vEldt jynx grImps wAqf zhO
bUck'.
Unlike backreferences, there is no speed penalty
for using match references, other than the extra
substitutions required for the replacement strings
in cases such as the example shown.
M Deactivate the m flag, hence no references to match
data will be created.
anum Approximate matching: num errors are allowed in the
string matched by the pattern. The rules for this
are described in the next subsection.
s, e Unlike the other flags, these have only a local
effect, and each must appear on its own: `(#s)'
and `(#e)' are the only valid forms. The `(#s)'
flag succeeds only at the start of the test string,
and the `(#e)' flag succeeds only at the end of the
test string; they correspond to `^' and `$' in
standard regular expressions. They are useful for
matching path segments in patterns other than those
any case treated separately). For example,
`*((#s)|/)test((#e)|/)*' matches a path segment
`test' in any of the following strings: test,
test/at/start, at/end/test, in/test/middle.
Another use is in parameter substitution; for exam
ple `${array/(#s)A*Z(#e)}' will remove only ele
ments of an array which match the complete pattern
`A*Z'. There are other ways of performing many
operations of this type, however the combination of
the substitution operations `/' and `//' with the
`(#s)' and `(#e)' flags provides a single simple
and memorable method.
Note that assertions of the form `(^(#s))' also
work, i.e. match anywhere except at the start of
the string, although this actually means `anything
except a zero-length portion at the start of the
string'; you need to use `(""~(#s))' to match a
zero-length portion of the string not at the start.
For example, the test string fooxx can be matched by the
pattern (#i)FOOXX, but not by (#l)FOOXX, (#i)FOO(#I)XX or
((#i)FOOX)X. The string (#ia2)readme specifies
case-insensitive matching of readme with up to two errors.
When using the ksh syntax for grouping both KSH_GLOB and
EXTENDED_GLOB must be set and the left parenthesis should
be preceded by @. Note also that the flags do not affect
letters inside [...] groups, in other words (#i)[a-z]
still matches only lowercase letters. Finally, note that
when examining whole paths case-insensitively every direc
tory must be searched for all files which match, so that a
pattern of the form (#i)/foo/bar/... is potentially slow.
Approximate Matching
When matching approximately, the shell keeps a count of
the errors found, which cannot exceed the number specified
in the (#anum) flags. Four types of error are recognised:
1. Different characters, as in fooxbar and fooybar.
2. Transposition of characters, as in banana and
abnana.
3. A character missing in the target string, as with
the pattern road and target string rod.
4. An extra character appearing in the target string,
as with stove and strove.
Thus, the pattern (#a3)abcd matches dcba, with the errors
once, grouping the string as [d][cb][a] and [a][bc][d].
Non-literal parts of the pattern must match exactly,
including characters in character ranges: hence (#a1)???
matches strings of length four, by applying rule 4 to an
empty part of the pattern, but not strings of length two,
since all the ? must match. Other characters which must
match exactly are initial dots in filenames (unless the
GLOB_DOTS option is set), and all slashes in filenames, so
that a/bc is two errors from ab/c (the slash cannot be
transposed with another character). Similarly, errors are
counted separately for non-contiguous strings in the pat
tern, so that (ab|cd)ef is two errors from aebf.
When using exclusion via the ~ operator, approximate
matching is treated entirely separately for the excluded
part and must be activated separately. Thus,
(#a1)README~READ_ME matches READ.ME but not READ_ME, as
the trailing READ_ME is matched without approximation.
However, (#a1)README~(#a1)READ_ME does not match any pat
tern of the form READ?ME as all such forms are now
excluded.
Apart from exclusions, there is only one overall error
count; however, the maximum errors allowed may be altered
locally, and this can be delimited by grouping. For exam
ple, (#a1)cat((#a0)dog)fox allows one error in total,
which may not occur in the dog section, and the pattern
(#a1)cat(#a0)dog(#a1)fox is equivalent. Note that the
point at which an error is first found is the crucial one
for establishing whether to use approximation; for exam
ple, (#a1)abc(#a0)xyz will not match abcdxyz, because the
error occurs at the `x', where approximation is turned
off.
Entire path segments may be matched approximately, so that
`(#a1)/foo/d/is/available/at/the/bar' allows one error in
any path segment. This is much less efficient than with
out the (#a1), however, since every directory in the path
must be scanned for a possible approximate match. It is
best to place the (#a1) after any path segments which are
known to be correct.
Recursive Globbing
A pathname component of the form `(foo/)#' matches a path
consisting of zero or more directories matching the pat
tern foo.
As a shorthand, `**/' is equivalent to `(*/)#'; note that
this therefore matches files in the current directory as
well as subdirectories. Thus:
or
ls **/bar
does a recursive directory search for files named `bar'
(potentially including the file `bar' in the current
directory). This form does not follow symbolic links; the
alternative form `***/' does, but is otherwise identical.
Neither of these can be combined with other forms of glob
bing within the same path segment; in that case, the `*'
operators revert to their usual effect.
Glob Qualifiers
Patterns used for filename generation may end in a list of
qualifiers enclosed in parentheses. The qualifiers spec
ify which filenames that otherwise match the given pattern
will be inserted in the argument list.
If the option BARE_GLOB_QUAL is set, then a trailing set
of parentheses containing no `|' or `(' characters (or `~'
if it is special) is taken as a set of glob qualifiers. A
glob subexpression that would normally be taken as glob
qualifiers, for example `(^x)', can be forced to be
treated as part of the glob pattern by doubling the paren
theses, in this case producing `((^x))'.
A qualifier may be any one of the following:
/ directories
. plain files
@ symbolic links
= sockets
p named pipes (FIFOs)
* executable plain files (0100)
% device files (character or block special)
%b block special files
%c character special files
r owner-readable files (0400)
w owner-writable files (0200)
x owner-executable files (0100)
I group-writable files (0020)
E group-executable files (0010)
R world-readable files (0004)
W world-writable files (0002)
X world-executable files (0001)
s setuid files (04000)
S setgid files (02000)
t files with the sticky bit (01000)
fspec files with access rights matching spec. This spec
may be a octal number optionally preceded by a `=',
a `+', or a `-'. If none of these characters is
given, the behavior is the same as for `='. The
octal number describes the mode bits to be
expected, if combined with a `=', the value given
must match the file-modes exactly, with a `+', at
least the bits in the given number must be set in
the file-modes, and with a `-', the bits in the
number must not be set. Giving a `?' instead of a
octal digit anywhere in the number ensures that the
corresponding bits in the file-modes are not
checked, this is only useful in combination with
`='.
If the qualifier `f' is followed by any other char
acter anything up to the next matching character
(`[', `{', and `<' match `]', `}', and `>' respec
tively, any other character matches itself) is
taken as a list of comma-separated sub-specs. Each
sub-spec may be either a octal number as described
above or a list of any of the characters `u', `g',
`o', and `a', followed by a `=', a `+', or a `-',
followed by a list of any of the characters `r',
`w', `x', `s', and `t', or a octal digit. The first
list of characters specify which access rights are
to be checked. If a `u' is given, those for the
owner of the file are used, if a `g' is given,
those of the group are checked, a `o' means to test
those of other users, and the `a' says to test all
three groups. The `=', `+', and `-' again says how
the modes are to be checked and have the same mean
ing as described for the first form above. The sec
ond list of characters finally says which access
rights are to be expected: `r' for read access, `w'
for write access, `x' for the right to execute the
and setgid bits, and `t' for the sticky bit.
Thus, `*(f70?)' gives the files for which the owner
has read, write, and execute permission, and for
which other group members have no rights, indepen
dent of the permissions for other users. The pat
tern `*(f-100)' gives all files for which the owner
does not have execute permission, and
`*(f:gu+w,o-rx:)' gives the files for which the
owner and the other members of the group have at
least write permission, and for which other users
don't have read or execute permission.
estring
The string will be executed as shell code. The
filename will be included in the list if and only
if the code returns a zero status (usually the sta
tus of the last command). The first character
after the `e' will be used as a separator and any
thing up to the next matching separator will be
taken as the string; `[', `{', and `<' match `]',
`}', and `>', respectively, while any other charac
ter matches itself. Note that expansions must be
quoted in the string to prevent them from being
expanded before globbing is done.
During the execution of string the filename cur
rently being tested is available in the parameter
REPLY; the parameter may be altered to a string to
be inserted into the list instead of the original
filename. In addition, the parameter reply may be
set to an array or a string, which overrides the
value of REPLY. If set to an array, the latter is
inserted into the command line word by word.
For example, suppose a directory contains a single
file `lonely'. Then the expression
`*(e:'reply=(${REPLY}{1,2})':)' will cause the
words `lonely1 lonely2' to be inserted into the
command line. Note the quotation marks.
ddev files on the device dev
l[-|+]ct
files having a link count less than ct (-), greater
than ct (+), or equal to ct
U files owned by the effective user ID
G files owned by the effective group ID
uid files owned by user ID id if it is a number, if
not, than the character after the `u' will be used
next matching separator (`[', `{', and `<' match
`]', `}', and `>' respectively, any other character
matches itself) will be taken as a user name, and
the user ID of this user will be taken (e.g.
`u:foo:' or `u[foo]' for user `foo')
gid like uid but with group IDs or names
a[Mwhms][-|+]n
files accessed exactly n days ago. Files accessed
within the last n days are selected using a nega
tive value for n (-n). Files accessed more than n
days ago are selected by a positive n value (+n).
Optional unit specifiers `M', `w', `h', `m' or `s'
(e.g. `ah5') cause the check to be performed with
months (of 30 days), weeks, hours, minutes or sec
onds instead of days, respectively. For instance,
`echo *(ah-5)' would echo files accessed within the
last five hours.
m[Mwhms][-|+]n
like the file access qualifier, except that it uses
the file modification time.
c[Mwhms][-|+]n
like the file access qualifier, except that it uses
the file inode change time.
L[+|-]n
files less than n bytes (-), more than n bytes (+),
or exactly n bytes in length. If this flag is
directly followed by a `k' (`K'), `m' (`M'), or `p'
(`P') (e.g. `Lk-50') the check is performed with
kilobytes, megabytes, or blocks (of 512 bytes)
instead.
^ negates all qualifiers following it
- toggles between making the qualifiers work on sym
bolic links (the default) and the files they point
to
M sets the MARK_DIRS option for the current pattern
T appends a trailing qualifier mark to the filenames,
analogous to the LIST_TYPES option, for the current
pattern (overrides M)
N sets the NULL_GLOB option for the current pattern
D sets the GLOB_DOTS option for the current pattern
n sets the NUMERIC_GLOB_SORT option for the current
oc specifies how the names of the files should be
sorted. If c is n they are sorted by name (the
default); if it is L they are sorted depending on
the size (length) of the files; if l they are
sorted by the number of links; if a, m, or c they
are sorted by the time of the last access, modifi
cation, or inode change respectively; if d, files
in subdirectories appear before those in the cur
rent directory at each level of the search --- this
is best combined with other criteria, for example
`odon' to sort on names for files within the same
directory. Note that a, m, and c compare the age
against the current time, hence the first name in
the list is the youngest file. Also note that the
modifiers ^ and - are used, so `*(^-oL)' gives a
list of all files sorted by file size in descending
order, following any symbolic links.
Oc like `o', but sorts in descending order; i.e.
`*(^oc)' is the same as `*(Oc)' and `*(^Oc)' is the
same as `*(oc)'; `Od' puts files in the current
directory before those in subdirectories at each
level of the search.
[beg[,end]]
specifies which of the matched filenames should be
included in the returned list. The syntax is the
same as for array subscripts. beg and the optional
end may be mathematical expressions. As in parame
ter subscripting they may be negative to make them
count from the last match backward. E.g.:
`*(-OL[1,3])' gives a list of the names of the
three largest files.
More than one of these lists can be combined, separated by
commas. The whole list matches if at least one of the sub
lists matches (they are `or'ed, the qualifiers in the sub
lists are `and'ed). Some qualifiers, however, affect all
matches generated, independent of the sublist in which
they are given. These are the qualifiers `M', `T', `N',
`D', `n', `o', `O' and the subscripts given in brackets
(`[...]').
If a `:' appears in a qualifier list, the remainder of the
expression in parenthesis is interpreted as a modifier
(see the section `Modifiers' in the section `History
Expansion'). Note that each modifier must be introduced
by a separate `:'. Note also that the result after modi
fication does not have to be an existing file. The name
of any existing file can be followed by a modifier of the
form `(:..)' even if no actual filename generation is per
formed. Thus:
lists all directories and symbolic links that point to
directories, and
ls *(%W)
lists all world-writable device files in the current
directory, and
ls *(W,X)
lists all files in the current directory that are
world-writable or world-executable, and
echo /tmp/foo*(u0^@:t)
outputs the basename of all root-owned files beginning
with the string `foo' in /tmp, ignoring symlinks, and
ls *.*~(lex|parse).[ch](^D^l1)
lists all files having a link count of one whose names
contain a dot (but not those starting with a dot, since
GLOB_DOTS is explicitly switched off) except for lex.c,
lex.h, parse.c and parse.h.
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