Q. How do I perform a case-insensitive search using sed under UNIX / Linux? I'd like to match all combination of word - foo, FOO, FoO and so on while replacing or performing other operations.
A. GNU sed and other version does support a case-insensitive search using I flag after /regex/.
UNIX / Linux: sed Case Insensitive Search
To perform a case-insensitive search, enter:
cat file.txt | sed -e 's/find-word/replace-word/gI' cat file.txt | sed -e 's/find-word/replace-word/gI' > output.txt sed 's/find-word/replace-word/gI' input.txt > output.txt
If you are using older sed version try,
sed 's/[wW][oO][rR][dD]/replace-word/g' input.txt > output.txt
It is easy to match first few characters, for example match both Linux and linux word:
sed 's/[Ll]inux/Unix/g' input.txt > output.txt