Howto implement AND in grep

No need for cat:

grep str1 file.txt grep str2 grep str3...

Either of the two scripts posted (by Michael Heiming and Peter Breuer) should give you a solution, but Michael's is not complete for your task.

I found this mgrep script I wrote a couple of years ago which does what you want. I don't think I've used it since; I probably wrote it in response to a similar question posted at the time. It expands on Michael's recommendation.

This works best with mawk, as it's faster than gawk.

# Mon Jan 13 13:28:19 EST 2003 # NAME: mgrep # USAGE: mgrep -e PAT1 -e PAT2 -e.... FILE ... # Copyright 2003, Chris F.A. Johnson # Released under the terms of the GNU General Public License

while getopts e: opt do case "$opt" in e) cmd="${cmd:+$cmd && }-$OPTARG-" ;; esac done shift $(( $OPTIND - 1 )) ####################################################

Peter's solution is a neat recursive function, but it requires cat and multiple calls to grep (as opposed to a single call to awk in the above script) making it slower as the number of patterns increases (but the difference decreases as file size increases).

For general use, patterns and file names need to be separated, and files catted, before the function can be called.

Here is a more general script using Peter's function, made more portable by avoiding "local", and enhancing performance by using -n rather then -le in the test, and grep rather than cat as the first command in the pipeline:

## Usage is the same as the above script mrgrep() { if -n "$*" ; then cat else mrgrepstr="$1" shift fi }

while getopts e: opt do case "$opt" in e) cmd="$cmd '$OPTARG'" ;; esac done

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