Unix if condition 1

[cisco999]

In the following code excerpt, please explain [ $? = 0 ] in the first if condition. Thank you.

java -XdoCloseWithReadPending -classpath .:UKtest.jaremandSchedule20.jar:$JDBC_PATH/classes111.zip hmi.common.uk.PullSignalConfirmExtract $ukFile $prod 2>err.out >> $LOGFILE
if [ $? = 0 ]
then
if [[ -s $ukFile ]]
then
. ukPricing_ftp.sh $ukServer $ukUser $ukPassword $ukFile mysign/$ukFile
grep -q '226 Transfer complete.' ftp.log
if [ $? -ne 0 ]
then
cat ftp.log | mailx -s " UK Pull Signal Confirm Extract: ftp to UK failed" ec_team@test.com
mv $ukFile $ukDir/data/error/$ukFile.$timestamp
else
mv $ukFile $ukDir/data/log/$ukFile.$timestamp
fi
else
echo "Nothing to extract. File has no data."
rm -f $ukFile
fi
else
cat err.out | mailx -s " UK Pull Signal Confirm Extract: Java Load failed" ec_team@test.com
mv $ukFile $ukDir/data/error/$ukFile.$timestamp
fi

 

[Chacalinc]

if [$? = 0] ask if the result of the las command was successful.

$? is the return code of the last command issued. It depend of the last command. example, a script can have an "exit 0" as the exit command, so $? will be 0, *but* if the exit command is another one, e.g. "exit 1" the $? will be 1.

ussualy, exit code 0 tells you that the command was finished sucessfuly.

Cheers,

Chacal, Inc.

 

[cisco999]

Thanks very much! The next if condition uses double brackets, [[ ]], what does that indicate? Do you have any websites that you would recommend for a beginner dealing with UNIX scripts?

 

[PHV]

THE starting point:
man yourshell
ie:
man ksh
man bash

Hope This Helps, PH.
Want to get great answers to your Tek-Tips questions? Have a look at FAQ219-2884 or FAQ181-2886

 

[stefanwagner]

http://freshmeat.net/projects/advancedbashscriptingguide/

is a nice guide for bash.

seeking a job as java-programmer in Berlin:

http://home.arcor.de/hirnstrom/bewerbung