sed¶

To substitute the first occurrence of a pattern on each line

sed 's/<pattern>/<replacement>/' <file>

To substitute all occurrences on each line (global)

sed 's/<pattern>/<replacement>/g' <file>

To edit a file in-place

sed -i 's/<pattern>/<replacement>/g' <file>

To edit in-place with a backup

sed -i.bak 's/<pattern>/<replacement>/g' <file>

To substitute only on lines matching a pattern

sed '/<line-pattern>/s/<pattern>/<replacement>/g' <file>

To delete lines matching a pattern

sed '/<pattern>/d' <file>

To delete blank lines

sed '/^$/d' <file>

To delete a specific line number

sed '5d' <file>

To delete a range of lines

sed '3,7d' <file>

To print only lines matching a pattern (like grep)

sed -n '/<pattern>/p' <file>

To print a specific line number

sed -n '5p' <file>

To print a range of lines

sed -n '3,7p' <file>

To insert a line before a matching line

sed '/<pattern>/i\<new line>' <file>

To append a line after a matching line

sed '/<pattern>/a\<new line>' <file>

To replace an entire matching line

sed 's/.*<pattern>.*/<replacement>/' <file>

To strip leading whitespace

sed 's/^[[:space:]]*//' <file>

To strip trailing whitespace

sed 's/[[:space:]]*$//' <file>

To strip both leading and trailing whitespace

sed 's/^[[:space:]]*//;s/[[:space:]]*$//' <file>

To replace tabs with spaces

sed 's/\t/  /g' <file>

To add a prefix to every line

sed 's/^/PREFIX: /' <file>

To remove a prefix from every line

sed 's/^PREFIX: //' <file>

To number lines

sed '=' <file> | sed 'N;s/\n/\t/'

To use extended regex (ERE)

sed -E 's/<ere-pattern>/<replacement>/g' <file>

To apply multiple expressions

sed -e 's/foo/bar/g' -e 's/baz/qux/g' <file>

To read replacement from a file

sed 's/<pattern>/<replacement>/g' <file> > <output>

To use & to refer to the matched text

sed 's/<pattern>/[&]/' <file>

To use capture groups (back-references)

sed 's/\(foo\)\(bar\)/\2\1/' <file>

With extended regex

sed -E 's/(foo)(bar)/\2\1/' <file>

To uncomment a line (remove leading #)

sed 's/^#//' <file>

To comment out a line (add leading #)

sed 's/^/#/' <file>

To update a key=value config line in-place

sed -i 's/^key=.*/key=newvalue/' <file>