Sed

Delete line that match

find /opt/beta/trac -name trac.ini -exec sed -i '/loginmodule/ D' {} \; -print

Change text in ruby files, -i inline, i.e. will modify existing files

find -name *.rb -exec sed -i -e 's/WikiVersion/WikiPage/g' {} \;

Sample sed command file with multiple edits.

1,/^END/{
  s|I18n.t.\"Spaces\".|I18n\.t\(\"space\"\, :count => 2)\.capitalize|g
  s|I18n.t.\"Space\".|I18n\.t\(\"space\"\)\.capitalize|g
  s|I18n.t.\"spaces\".|I18n\.t\(\"space\"\, :count => 2)|g
}