How do I perform a case-insensitive search using sed under UNIX-like or Linux operating system? I would like to match all combination of word – foo, FOO, FoO and so on while replacing or performing other operations using sed command.
GNU sed and other version does support a case-insensitive search using I flag after /regex/.
UNIX / Linux: sed Case Insensitive Search and Replace
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 |
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 |
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 |
sed ‘s/[Ll]inux/Unix/g’ input.txt > output.txt
The BSD implementation of sed does NOT support case-insensitive matching
If you are on macOS install GNU sed using the following brew command:
$ brew install gnu-sed
Sample outputs:
Updating Homebrew... ==> Auto-updated Homebrew! Updated 1 tap (homebrew/core). No changes to formulae. ==> Downloading https://homebrew.bintray.com/bottles/gnu-sed-4.4.sierra.bottle.tar.gz Already downloaded: /Users/veryv/Library/Caches/Homebrew/gnu-sed-4.4.sierra.bottle.tar.gz ==> Pouring gnu-sed-4.4.sierra.bottle.tar.gz ==> Using the sandbox ==> Caveats The command has been installed with the prefix "g". If you do not want the prefix, install using the "with-default-names" option. If you need to use these commands with their normal names, you can add a "gnubin" directory to your PATH from your bashrc like: PATH="/usr/local/opt/gnu-sed/libexec/gnubin:$PATH" Additionally, you can access their man pages with normal names if you add the "gnuman" directory to your MANPATH from your bashrc as well: MANPATH="/usr/local/opt/gnu-sed/libexec/gnuman:$MANPATH" ==> Summary ? /usr/local/Cellar/gnu-sed/4.4: 12 files, 491KB
Now use gsed command as follows:
cat file.txt | gsed -e 's/find-word/replace-word/gI' cat file.txt | gsed -e 's/find-word/replace-word/gI' > output.txt gsed 's/find-word/replace-word/gI' input.txt > output.txt |
cat file.txt | gsed -e ‘s/find-word/replace-word/gI’
cat file.txt | gsed -e ‘s/find-word/replace-word/gI’ > output.txt
gsed ‘s/find-word/replace-word/gI’ input.txt > output.txt
Another option is to use perl command for case-insensitive search & replace:
## find foo and replace with bar case-insensitive ## perl -pi -e 's/foo/bar/gi' input.txt |
## find foo and replace with bar case-insensitive ##
perl -pi -e ‘s/foo/bar/gi’ input.txt
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