I've always found the `find` and xargs command pair to be the quickest way to demonstrate the unix philosophy. For example, consider, if we want to do this ...

I've always found the `find` and xargs command pair to be the quickest way to demonstrate the unix philosophy. For example, consider, if we want to do this ... # inplace (-i), execute (-e), subtitution of the regular expression 'Pattern' (s/Pattern/), # with the word 'Substitution' (Substitution/), on all matches (g) in file 'filename', you'd do ... $ sed -i -e 's/Pattern/Substitution/g' <filename> # Now if you want to do this for all text files under a directory tree ... $ find -name '.txt' | xargs sed -i -e 's/Pattern/Substitution/g' # ...while limiting it to just 2 levels of 'depth' ... $ find -name '.txt' -maxdepth 2 | xargs sed -i -e 's/Pattern/Substitution/g' # ...and for only those that were modified yesterday ... ... # ...belonging to a certain user .... ... you get the idea. Other good tools that fall in the similar category are 'sort', 'uniq', 'tr' ...etc. Eg: $ find /tmp/ -type f -exec stat -c "%s %n" {} \; | sort -n