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Please help on IF statements.

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Top Forums Shell Programming and Scripting Please help on IF statements.
# 1  
Old 07-18-2007
Please help on IF statements.
I had different problem scenarios with IF statement. Can any expert please enlighten me on the difference with these scenarios. Thank you.

1st Scenario:

Code:
testdate=`date +%Y%m`
test=`cat /var/log/database0.$testdate*.log | grep "Errors found during processing" | tail -10`
if [ -z $test ]
then
        echo "No Error" >> $$.tmp
else
        echo "Error Found" >> $$.tmp
        cat /var/log/database0.$testdate*.log | grep "No files found for processing" | tail -10 >> $$.tmp
        echo " " >> $$.tmp
fi

Anyone knows why will the below error occur when i run the script above?

./test.sh: test: argument expected

2nd Scenario:

Code:
test=`cat /var/log/database0*.log | grep "Errors found during processing" | tail -10`
if [ -z $test ]
then
        echo "No Error" >> $$.tmp
else
        echo "Error Found" >> $$.tmp
        cat /var/log/database0.$testdate*.log | grep "No files found for processing" | tail -10 >> $$.tmp
        echo " " >> $$.tmp
fi

For the above code it will work.

3rd Scenario:

Code:
test=`grep error /var/log/database0*.log | tail -10`
if [ -z $test ]
then
        echo "No Error" >> $$.tmp
else
        echo "Error Found" >> $$.tmp
        cat /var/log/database0.$testdate*.log | grep "No files found for processing" | tail -10 >> $$.tmp
        echo " " >> $$.tmp
fi

The above code don't work and after i change it to the one below it works.

Code:
test=`grep error /var/log/database0*.log | tail -10`
if [ $test=" " ]
then
        echo "No Error" >> $$.tmp
else
        echo "Error Found" >> $$.tmp
        cat /var/log/database0.$testdate*.log | grep "No files found for processing" | tail -10 >> $$.tmp
        echo " " >> $$.tmp
fi

# 2  
Old 07-18-2007
Hi,
For the first scenario if the value of test is empty you may be getting the error.
This can be avoided by putting test inside quotes like if [ -z "$test" ]

if [ $test=" " ] this condition will give u error as there is a missing space between .It should be if [ $test = " " ]

Raghuram
# 3  
Old 07-18-2007
Thanks Raghuram
# 4  
Old 07-18-2007
you can do it like that without the -z and without the quotes safely

if [ $thang ] ; then


because [ ] evaluates as false anyway.
# 5  
Old 07-18-2007
hi
i guess

u have to give semi colan after the braces and then follows


if [ ] ; then
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