if command not having the right output - Shell Programming and Scripting

filthymonk · #1 (**permalink**) 05-22-2007

Code:

if cat /var/log/messages | grep fail = " "  
then 
echo "Good"
else
echo "Bad"
fi

i have 10 files named messages.0 , messages.1 , .... till 9 then i need cat all the files and grep to see if there is anything failing. therefore, i used the above command however, it doesn't seems to be working please help.

porter · #2 (**permalink**) 05-22-2007

You need backquotes to capture output
Then double quotes to make it a single argument for test
And you need test
And it should be a truely empty string

Code:

if test "`cat /var/log/messages | grep fail`" = ""  
then 
echo "Good"
else
echo "Bad"
fi

alternatively use

Code:

if test -z "`cat /var/log/messages | grep fail`" 
...

But you could get rid of all the above with

Code:

if grep fail /var/log/messages
then
     echo failed
else
     echo no problems
fi

lorcan · #3 (**permalink**) 05-22-2007

#!/bin/sh

LOG_FILE=log.txt
grep -l fail /var/log/messages* > $LOG_FILE
if [$? -eq 0]
then
echo "Bad"
echo "Files that contains failures are"
cat $LOG_FILE
else
echo "Good"
fi
exit

filthymonk · #4 (**permalink**) 05-22-2007

thank you all for the prompt reply ! All of the info provided is very useful to me thanks !

filthymonk · #5 (**permalink**) 05-22-2007

Code:

#!/bin/sh

LOG_FILE=log.txt
grep -l fail /var/log/messages* > $LOG_FILE
if [$? -eq 0]
then 
      echo "Bad"
      echo "Files that contains failures are"
      cat $LOG_FILE
else
      echo "Good"
fi
exit

[$? -eq 0]

$? ==> unknown variable or all variable ?
-eq ==> equals ?

ghostdog74 · #6 (**permalink**) 05-22-2007

Code:

awk '/[Ff]ail/{filename[FILENAME];nextfile}END{for (i in filename) print i }' /var/log/messages*

lorcan · #7 (**permalink**) 05-22-2007

filthymonk i am just checking the status of the execution of the grep command so i have used ($? variable) and checking for 0

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