Gnu sed: Difference between revisions
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# 's' command search/replaces text | # 's' command search/replaces text | ||
echo 'foo_bar_baz' | sed 's/bar/BAR/g' | echo 'foo_bar_baz' | sed 's/bar/BAR/g' | ||
> | > foo_BAR_gaz | ||
# 'i'/'a' commands prepend/append newlines to each line | # 'i'/'a' commands prepend/append newlines to each line |
Revision as of 13:51, 16 October 2021
Gnu sed performs search/replace within stdin or files.
See also bsd sed.
Overview
sed lets you manipulate text streams using commands.
example commands:
# 's' command search/replaces text echo 'foo_bar_baz' | sed 's/bar/BAR/g' > foo_BAR_gaz # 'i'/'a' commands prepend/append newlines to each line echo 'foo\nbar\nbaz' | sed 'i \my newline' > my newline > foo > my newline > bar > my newline > bazBy default, all commands operate on every line.
You can use addresses to limit the scope of a command.# Limit scope of 'i' command to lines matching /bar/ echo 'foo\nbar\nbaz' | sed '/bar/i \my newline' > foo > my newline > bar > baz
Usage
# Replace 'aaa' with 'bbb' cat echo "aaa_stuff_aaa" \ | sed 's_aaa_bbb_g' # Regex cat echo "aaa_stuff_aaa" \ | sed -E 's_[a]*_b_g' # Group matching (\2 is a variable that refers to the # second match group. In this case, 'stuff' cat echo "aaa_stuff_aaa" \ | sed -E 's_\([a]*\)\(stuff\)_\2\n' # Replace file contents sed -i"bak" "s_aaa_bbb_g" /path/to/file