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Comparing two strings those are outputs of echo

 
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# 1  
Old 03-20-2009
Question Comparing two strings those are outputs of echo
Hello,

I have two strings those are outputs of two echo commands:

Code:
$ logslist=`ls -1rt vp_lb_indv*.log | tail -1`; tail -7 $logslist | head -1          
ERROR: Errors printed on pages 5,22.
$ logslist=`ls -1rt vp_lb_indv*.log | tail -1`; errpages=`tail -7 $logslist | head -1`; echo $errpages
ERROR: Errors printed on pages 5,22.
$

Now, I expect following command returns 1:

Code:
$ logslist=`ls -1rt vp_lb_indv*.log | tail -1`; errpages=`tail -7 $logslist | head -1`; if [ '`echo $errpages`' = '`echo ERROR: Errors printed on pages 5,22.`' ]; then expr 1 / 1; else expr 1 / 0; fi
expr: division by zero
$

But it produces the devision by zero error, which I expect only when two strings are not equal.

I need a command/script to produce an OS error if the line I purged from a specific log file is not equal to a specific string.

Thank you very much,
Last edited by Yogesh Sawant; 03-25-2009 at 05:28 AM.. Reason: added code tags
# 2  
Old 03-20-2009
You dont need all the extra "echo" commands for one thing. Also, you need to use double quotes. The only time you should not use double quotes in the shell, are when yo uhave special characters that you mean to interpret literally. Such as if i want to say:

Code:
$ echo '$var is not set'
$var is not set

Your code:

Code:
if [ '`echo $errpages`' = '`echo ERROR: Errors printed on pages 5,22.`' ]

SHOULD be:

Code:
if [ "$errpages" = "ERROR: Errors printed on pages 5,22." ]

notice how we got rid of the "echo" commands, and put everything in DOUBLE quotes....the variable, and the string you are comparing the variable to.

This should work for you now.
# 3  
Old 03-20-2009
I modified the code, but it still gives the devision by zero error Smilie
# 4  
Old 03-23-2009
MySQL Purging Log Files
I couldn't find why the above comparision fails, but I found the way that I need:

Code:
logslist=`ls -1rt vp_lb_indv*.log | tail -1`; errpages=`grep -c 'ERROR:' $logslist`; if [ $errpages = 5 ]; then expr 1 / 1; else expr 1 / 0; fi

If someone find why, please share with us Smilie
Last edited by Yogesh Sawant; 03-25-2009 at 05:25 AM.. Reason: added code tags
 
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