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Re: `if $(cmd);' is a positive when there's no output from cmd
From: |
Herculano Einloft |
Subject: |
Re: `if $(cmd);' is a positive when there's no output from cmd |
Date: |
Sat, 15 Apr 2006 23:23:15 -0300 |
Em (02:25:11), Andreas Schwab escreveu:
>
>> Hey all,
>>
>> $ if $(echo string >/dev/null); then echo true; fi
>> true
>>
>> This should be a syntax error
>
>No, it is a perfectly valid command, syntactically. That the command
>substitution expands to nothing has no significance any more once the
>command is parsed, just like shell meta characters resulting from
>expansions are taken literally.
>
>Andreas.
That's not true.. try:
$ echo $(echo \*)
or
$ a=*; echo "$a"; echo $a
for illustration.
Regards