Problem scenario: How do you use the grep command to recursively search most subdirectories (excluding some directories) for a pattern? You want to find a file with a string like this:
/var/lib/pgsql/data
You are not interested in the files in directory paths that have one or more parent (or any antecedent) directories named "proc" nor "sys". You want to list files that have the above pattern. You want the results that match the string above in a case-insensitive way. What do you do?
Solution
Grepping for patterns with forward slashes don't require quotes around the patterns when using the grep command. Searching for lower case patterns with the "-i" flag will return files that match the string's pattern in lower case or in upper case or in any combination thereof. Knowing that you want to exclude any file that resides in a directory path having a directory with the name "proc" or "sys" can make the search quicker. The "--exclude-dir=" flag allows you to exclude results with "proc" or "sys" directories. These exclude-dir flags will exclude any directory path with "proc" or "sys" -- not just the root "proc" and "sys" directories.
Follow these steps:
1. cd /
2. grep -ir /var/lib/pgsql/data . --exclude-dir=proc --exclude-dir=sys
To clarify the step #2 command, it will return files with a string matching the pattern /var/lib/pgsql/data except those files that are in a path with a directory named "proc" or "sys".