I've seen something along the lines of
if ! some-command; then #do something fi What's the effect of the exclamation point? I see that if you use brackets, it can be used for negation.
Is that the same effect here?
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2 Answers
As documented in man bash:
If the reserved word
!precedes a pipeline, the exit status of that pipeline is the logical negation of the exit status as described above.
Comments
Correct.
Here is a code sample:
anny ~> if ! grep $USER /etc/passwd More input> then echo "your user account is not managed locally"; fi your user account is not managed locally anny > echo $? 0 anny > Source: http://tldp.org/LDP/Bash-Beginners-Guide/html/sect_07_01.html
2 Comments
alvits
echo $? will always return 0 because the exit status of the if...then...fi block is 0. Try it with different combination and you will see that it will always be 0 even when the if statement is broken, such as syntax errors.alvits
In short, the exit status of the
if...fi block is the exit status of the list within the block, not the exit status of the condition.