Linux – How to search for strings in a file which in turn is in an archive

Try

find /srv/www/*/htdocs/system/application/ -name "*.php" -exec grep "debug (" {} \; -print

This should recursively search the folders under application for files with .php extension and pass them to grep.

An optimization on this would be to execute:

find /srv/www/*/htdocs/system/application/ -name "*.php" -print0 | xargs -0 grep -H "debug ("

This uses xargs to pass all the .php files output by find as arguments to a single grep command; e.g., grep "debug (" file1 file2 file3. The -print0 option of find and -0 option of xargs ensure the spaces in file and directory names are correctly handled. The -H option passed to grep ensures that the filename is printed in all situations. (By default, grep prints the filename only when multiple arguments are passed in.)

From man xargs:

-0

Input items are terminated by a null character instead of by whitespace, and the quotes and backslash are not special (every character is taken literally).  Disables the end of file string, which is treated like any other argument.  Useful when input items might contain white space, quote marks, or backslashes.  The GNU find -print0 option produces input suitable for this mode.

Adding to Ansgar’s answer, consider -l (lower-case L) instead of -c.   It (-l) will give you a yes or no answer.

/run/command/outputting/numbers | grep –l '^456$'

will output “(standard input)” and exit with a status of 0 if a matching line is found; if the text is not found, it will output nothing and exit with a status of 1.  Some versions of grep also support a -q (quiet) option, which will suppress all output and give only the exit status.

These have the advantage that they are able to exit upon encountering the search string for the first time, and do not need to read the entire input.  If you need your command to run to completion, these options may be harmful.