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I am trying to find the installation directory of a particular package. I have a certain keyword using which I am trying to find a particular file.

During grep, I only want to include cpp or h file type. I do not want the grep to show warnings like Permission Denied or Could not find the Directory. I just want it to display matched files, nothing else. Please suggest how can I do this?

At present I am using

grep "My term" -ir --exclude-dir="\.svn" --include=*.{cpp,h} ./
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3 Answers 3

up vote 12 down vote accepted

Those warnings are directed to the stderr, as opposed to the standard out file descriptor. You can silence the stderr output by adding "2>/dev/null" to the end of your command.

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More directly than filtering the warnings you can disable them by adding -s:

grep "My term" -sir --exclude-dir="\.svn" --include=*.{cpp,h} ./

There are some compatibility issues with this option. However, this shouldn't be a problem for personal use.

-s, --no-messages: Suppress error messages about nonexistent or unreadable files. Portability note: unlike GNU grep, 7th Edition Unix grep did not conform to POSIX, because it lacked -q and its -s option behaved like GNU grep's -q option. USG-style grep also lacked -q but its -s option behaved like GNU grep. Portable shell scripts should avoid both -q and -s and should redirect standard and error output to /dev/null instead. (-s is specified by POSIX.)

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I just installed 13.04 and I am getting the errors which I was not getting with 12.04. Could it be that something changed? I thought it was cool that grep would stop warning about files being directories since in most cases I just don't care! –  Alexis Wilke Oct 12 '13 at 20:34
Sorry, I am still on 12.10, so I cannot confirm this. –  Sebastian vom Meer Oct 13 '13 at 16:07

When doing recursive searches in specific files, you are much better off using ack-grep. The syntax here would be: $ ack-grep -i "My term" --cpp --h

To remove the permission error messages, you may want to run the same command with sudo: $ ack-grep -i "My term" --cpp --h

But eventually, if you want to search installed packages, look at those various options: https://www.google.fr/search?q=ubuntu%20search%20inside%20installed%20packages

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