sed sed
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Jump to navigationJump to searchfind part of a line, substitute, keep rest of time intact
sed -i -e "s/^#DatabaseDirectory \(.*\)/DatabaseDirectory \\1/" myfile.txt
find pattern in a line, insert new line before it
This finds line that begins with exit(ignore leading spaces), then insert 'authdarmond start' before it.
sed -i -e "/^\\s*exit/i/authdaemond start" /etc/rc.local;
find pattern and append line
Note how replace pattern spans multiple lines
sed -i -e '/#!\/bin\/sh/a\ QMAILQUEUE="/var/qmail/bin/qmail-scanner-queue.pl" ; export QMAILQUEUE' /var/qmail/supervise/qmail-smtpd/run