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users/11366 (belated commit): update documentation for ${var:-word} and

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related expressions.
This commit is contained in:
Bart Schaefer 2007-05-30 03:08:22 +00:00
parent 5af264a642
commit eb3252d67b
1 changed files with 24 additions and 24 deletions
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48
Doc/Zsh/expn.yo
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@ -486,39 +486,39 @@ item(tt(${PLUS())var(name)tt(}))(
If var(name) is the name of a set parameter `tt(1)' is substituted,
otherwise `tt(0)' is substituted.
)
xitem(tt(${)var(name)tt(-)var(word)tt(}))
item(tt(${)var(name)tt(:-)var(word)tt(}))(
If var(name) is set and is non-null then substitute its
value; otherwise substitute var(word). If var(name) is
missing, substitute var(word).
Note that you can use standard shell quoting in the var(word) value to
selectively override the splitting done by the tt(SH_WORD_SPLIT) option
and the tt(=) flag, but not the tt(s:)var(string)tt(:) flag.
If var(name) is set, or in the second form is non-null, then substitute
its value; otherwise substitute var(word). In the second form var(name)
may be omitted, in which case var(word) is always substituted.
)
xitem(tt(${)var(name)tt(PLUS())var(word)tt(}))
item(tt(${)var(name)tt(:PLUS())var(word)tt(}))(
If var(name) is set, or in the second form is non-null, then substitute
var(word); otherwise substitute nothing.
)
xitem(tt(${)var(name)tt(=)var(word)tt(}))
xitem(tt(${)var(name)tt(:=)var(word)tt(}))
item(tt(${)var(name)tt(::=)var(word)tt(}))(
In the first form, if var(name) is unset or is null then
set it to var(word); in the second form, unconditionally
set var(name) to var(word). In both forms, the value of
the parameter is then substituted.
In the first form, if var(name) is unset then set it to var(word); in the
second form, if var(name) is unset or null then set it to var(word); and
in the third form, unconditionally set var(name) to var(word). In all
forms, the value of the parameter is then substituted.
)
xitem(tt(${)var(name)tt(?)var(word)tt(}))
item(tt(${)var(name)tt(:?)var(word)tt(}))(
If var(name) is set and is non-null then substitute
its value; otherwise, print var(word) and exit from the shell.
Interactive shells instead return to the prompt.
If var(word) is omitted, then a standard message is printed.
)
item(tt(${)var(name)tt(:PLUS())var(word)tt(}))(
If var(name) is set and is non-null then substitute
var(word); otherwise substitute nothing.
Note that you can use standard shell quoting in the var(word) value to
selectively override the splitting done by the tt(SH_WORD_SPLIT) option
and the tt(=) flag, but not the tt(s:)var(string)tt(:) flag.
In the first form, if var(name) is set, or in the second form if var(name)
is both set and non-null, then substitute its value; otherwise, print
var(word) and exit from the shell. Interactive shells instead return to
the prompt. If var(word) is omitted, then a standard message is printed.
)
enditem()
If the colon is omitted from one of the above expressions
containing a colon, then the shell only checks whether
var(name) is set, not whether its value is null.
In any of the above expressions that test a variable and substitute an
alternate var(word), note that you can use standard shell quoting in the
var(word) value to selectively override the splitting done by the
tt(SH_WORD_SPLIT) option and the tt(=) flag, but not splitting by the
tt(s:)var(string)tt(:) flag.
In the following expressions, when var(name) is an array and
the substitution is not quoted, or if the `tt((@))' flag or the