$? means?


 
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# 1  
Old 11-03-2008
$? means?

Hi All,
Can you please explain wats the meaning of this

$?

in unix
Thanks
# 2  
Old 11-03-2008
$? means that the return code of the previous command. When you write a script, we need to ensure that the command has successful or not. This will be done by checking the return code of the previous command. i.e $?

Upon successful execution of command, it will return the code 0 else non-negative no.
For ex:

$ rm tmp
$ echo $?
0

$ ls tmp
ls: tmp: No such file or directory
$ rm tmp
rm: cannot remove `tmp': No such file or directory
$ echo $?
1
# 3  
Old 11-03-2008
thanks
 
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