On 08.05.2009 17:10, Alan McKinnon wrote: >>> if echo hello|grep --color=auto l >/dev/null 2>&1; then >>> export GREP_OPTIONS='--color=auto' GREP_COLOR='1;32' >>> fi >>> >>> to ~/.bashrc >>> >>> Why does he echo hello, please? >> Some greps (like BSD one) might not support '--color' option, so "echo >> hello|grep --color=auto l" will return error code, skipping if clause, >> and won't break grep operation by adding an unsupported option. > > except that STDERR is combined with STDOUT and sent to /dev/null so the > script > will never get it, the if is always true and the entire check is redundant. > Better would be > > if echo hello|grep --color=auto l >/dev/null ; then
No. We do not want any output from echo|grep. We just want the exit code so that the following export statement gets executed iff grep returns with no errors. -- Eray
