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why isn't the exit status true?

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Top Forums Shell Programming and Scripting why isn't the exit status true?
# 1  
Old 04-04-2007
why isn't the exit status true?
the code:

do
[ -d ${mk_backup_dir[$i]} ] || mkdir -p ${mk_backup_dir[$i]}
[ $? -ne 0 ] && echo "ERROR: release backup directory creation failed -${mk_backup_dir[$i]}" && exit
done

echo "INFO: Backup directories created"


the result:

mkdir: "/cm/uat_releases/riab/uat/2345": Permission denied
ERROR: release backup directory creation failed - /cm/uat_releases/riab/uat/2345
No such file or directory

INFO: Backup directories created


isn't the exit status of the first command on the 3rd line 'true', so therefore the script will exit '&& exit'? but it doesn't, it carries on and displays 'Backup directories created'.

why?
# 2  
Old 04-04-2007
have you echoed $? to see what is returned?
Code:
[ -d ${mk_backup_dir[$i]} ] || mkdir -p ${mk_backup_dir[$i]}
echo $?


You could also use debugging
Code:
#!/usr/bin/ksh
{
set -x 
do
[ -d ${mk_backup_dir[$i]} ] || mkdir -p ${mk_backup_dir[$i]}
[ $? -ne 0 ] && echo "ERROR: release backup directory creation failed -${mk_backup_dir[$i]}" && exit
done

set +x
} >> outputlog 2>&1

Last edited by OFFSIHR; 04-04-2007 at 08:46 AM..
# 3  
Old 04-04-2007
Quote:
Originally Posted by OFFSIHR
have you echoed $? to see what is returned?
Code:
[ -d ${mk_backup_dir[$i]} ] || mkdir -p ${mk_backup_dir[$i]}
echo $?


You could also use debugging
Code:
#!/usr/bin/ksh
{
set -x 
do
[ -d ${mk_backup_dir[$i]} ] || mkdir -p ${mk_backup_dir[$i]}
[ $? -ne 0 ] && echo "ERROR: release backup directory creation failed -${mk_backup_dir[$i]}" && exit
done

set +x
} >> outputlog 2>&1


$? = 2. which is not zero. therefore '&& echo "Error:....' gets displayed and then the exit should follow.
# 4  
Old 04-04-2007
mmmmm you're right the exit should follow
I've just tested it using this
Code:
#!/usr/bin/ksh
{
set -x
arg=0
while [[ $arg -le 1 ]]
do
[ -d /cm/uat_releases/riab/uat/2345 ] || mkdir -p /cm/uat_releases/riab/uat/2345
[ $? -ne 0 ] && echo "ERROR: release backup directory creation failed -/cm/uat_releases/riab/uat/2345" && exit
(( arg +=1 ))
done

echo "INFO: Backup directories created"
set +x
}>> ouptput 2>&1

It DOES work and exits WITHOUT displaying
Code:
INFO: Backup directories created

my debugging info was
Code:
 arg=0
+ [ -d /cm/uat_releases/riab/uat/2345 ]
+ mkdir -p /cm/uat_releases/riab/uat/2345
mkdir: cannot create directory `/cm': Permission denied
+ [ 1 -ne 0 ]
+ echo ERROR: release backup directory creation failed -/cm/uat_releases/riab/uat/2345
ERROR: release backup directory creation failed -/cm/uat_releases/riab/uat/2345
+ exit

btw my machine details are Linux fhinux 2.6.5-7.191-default #1 Tue Jun 28 14:58:56 UTC 2005 i686 i686 i386 GNU/Linux

and i'm using korn
# 5  
Old 04-04-2007
Quote:
Originally Posted by OFFSIHR
mmmmm you're right the exit should follow
I've just tested it using this
Code:
#!/usr/bin/ksh
{
set -x
arg=0
while [[ $arg -le 1 ]]
do
[ -d /cm/uat_releases/riab/uat/2345 ] || mkdir -p /cm/uat_releases/riab/uat/2345
[ $? -ne 0 ] && echo "ERROR: release backup directory creation failed -/cm/uat_releases/riab/uat/2345" && exit
(( arg +=1 ))
done

echo "INFO: Backup directories created"
set +x
}>> ouptput 2>&1

It DOES work and exits WITHOUT displaying
Code:
INFO: Backup directories created

my debugging info was
Code:
 arg=0
+ [ -d /cm/uat_releases/riab/uat/2345 ]
+ mkdir -p /cm/uat_releases/riab/uat/2345
mkdir: cannot create directory `/cm': Permission denied
+ [ 1 -ne 0 ]
+ echo ERROR: release backup directory creation failed -/cm/uat_releases/riab/uat/2345
ERROR: release backup directory creation failed -/cm/uat_releases/riab/uat/2345
+ exit

btw my machine details are Linux fhinux 2.6.5-7.191-default #1 Tue Jun 28 14:58:56 UTC 2005 i686 i686 i386 GNU/Linux

and i'm using korn
i got it to work. it's my fault.

in the script, i'm using a function called 'display_message' instead of 'echo'. i omitted this from my post and replaced it with 'echo' because i couldn't be bothered to explain the function.

Quote:
function Display_Message
{
echo "$*" | tee -ai $LOGFILE
}
$LOGFILE isn't setup properly yet, so i was actually getting an error before '&& exit' was reached. somehow - not sure how though - this was causing the '&& exit' to be ignored.

thanks offsihr, because it was from running your version of the script that helped me realise my mistake.
# 6  
Old 04-04-2007
you're welcome.
sometimes it's easier when someone else does a cut down.
I'm guessing short circuit evaluation meant the whole expression wasn't evaluated

http://en.wikipedia.org/wiki/Minimal_evaluation

[ $? -ne 0 ] && echo "ERROR: release backup directory creation failed -/cm/uat_releases/riab/uat/2345" && exit
TRUE---------------------->FALSE------------------------------------------> no more is evaluated

as && needs all to be true
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