Shell Programming and Scripting

Hi everyone,

Looking at writing another awk program here to find a pattern on a text file. If patterns aren't found I want the awk program to exit and then bash to file a failure log on the local machine. Then later a management framework we have in place will read if that failure log file exists and flag the computer as being failed in our database.

I am pretty good with my bash skills but awk and sed still hang me up from time to time and I cannot wrap my head around this one so figure I'd ask the gurus here, as I am probably just being an idiot on how this works.

Here is an example:

Code:

#!/bin/bash

sourceFile="/path/to/file/with/patterns"

if [[ awk -F, '/pattern/ {print $2, exit}' ${sourceFile} == new_pattern ]]
then do various tasks
else echo "renaming failed" > /var/logs/failure.log
exit 1
fi

new_pattern is determined by a variable parsing through the source file. I am still testing out various ways of doing this. Find command, data array, and also sourcing the list of proper names. The file is comma separated. I am also passing the /pattern/ part from bash as a variable. That works.

This is hanging up so I think I need to do he if statement in awk and not use bash. However, if the pattern matches the script works fine. This is great, but I need some way to track down failures down the road and manually fix them. Basically, I work for a company that has merged with other companies and having to bring everything up to the new parent company's standards (naming conventions of files, folders, etc) So I am matching patterns of what the standards should be, versus what they are currently named (supplied via master text file from remote offices) and then trying to automate the process. Tons of computers out in the wild right now. There are going to be failures because of certain unknowns.

So, I am trying some if statements in awk instead:

Code:

awk -F, 'if ($1 ~ /^$pattern/){ print $2, exit }' ${sourceFile};
else exit 1

This seems to not be working as I intended. Sorry for the probably easy noob question but I am not wrapping my head around this. Currently reading through my awk books as well.

Thanks a ton in advance

Just making awk exit early doesn't make it return error, you need 'exit 1'.

Variables don't expand inside single quotes, either.

Code:

if awk -v P="$pattern" 'P ~ $0 { exit 1 }'
then
        echo "Awk succeeded"
else
        echo "Awk returned error"
fi

Though you could as easily use grep with inverted logic, as it will return 1 when not found and 0 when found:

Code:

if grep -l "$pattern" filename > /dev/null
then
        echo "Pattern found in file"
else
        echo "Pattern not found in file"
fi

Wow, you're good. Yes, my script expands the variable properly with the proper quotes I just didn't copy/paste the right from my script.

Also, running grep beforehand to make sure those are in the master list is actually an easier approach, and I knew that but didn't think of it. Again, good thinking.

I am thinking of this:

Code:

grep -l "pattern" /path/to/inputfile.txt

if [[ `/bin/echo "$?"` -eq 0 ]]
then echo "pattern found"
else echo "pattern not found..."
echo "procedure failed" > /var/log/failure.log
exit 1
fi

Unless there is a good reason I should not check the exit status of grep?

This at least gives me something to work with. Thanks again mate!

You can also use the return code of grep directly:

Code:

if grep -l "pattern" /path/to/inputfile.txt
then

To suppress output of grep:

Code:

if grep -q "pattern" ...

or

Code:

if grep "pattern" ... > /dev/null 2>&1