"June Fang" <[EMAIL PROTECTED]> writes:
> i know ${ZSH_VERSION} means variable substituting;
> and ${ZSH_VERSION:+set} means "If parameter is null or unset, nothing
> ~~ Note the `:`
> is substituted, otherwise the expansion of word is substituted."
> ---- from Bash reference manual
>
> but what dose ${ZSH_VERSION+set} without the `:` means ?
See the Bash menual (same section):
When not performing substring expansion, Bash tests for a parameter
that is unset or null; omitting the colon results in a test only for a
parameter that is unset. Put another way, if the colon is included,
the operator tests for both existence and that the value is not null;
if the colon is omitted, the operator tests only for existence.
Andreas.
--
Andreas Schwab, SuSE Labs, [EMAIL PROTECTED]
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
PGP key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
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