CODEWITHSUNDEEP
regexsed
Marcelo Guedes
Marcelo Guedes

Reputation: 1535

Sed: Use matched text in substitution

How can I use sed so that when it finds a match, I can use it in the substitution field?

For example

echo "12a34" | sed 's/a/#bcd/g'
12abcd34

What do I replace the # with to get the expected result?

Upvotes: 0

Views: 247

Answers (1)

Wintermute
Wintermute

Reputation: 44043

Use &:

echo '12a34' | sed 's/a/&bcd/g'
12abcd34

& in the replacement clause of a s/// command refers to what the pattern matched, which is the a in this case.

This particular case doesn't show very well how it works, since a is not a very interesting regular expression, so let me add a better example:

echo foobar | sed 's/[fb]/&42/g'
f42oob42ar

where the f and the b are matched by [fb] and subsequently replaced with f42 and b42.

Upvotes: 4

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