CODEWITHSUNDEEP
regexbashsed
Camden S.
Camden S.

Reputation: 2245

replace a unknown string between two known strings with sed

I have a file with the following contents:

WORD1 WORD2 WORD3

How can I use sed to replace the string between WORD1 and WORD3 with foo, such that the contents of the file are changed to the following?:

WORD1 foo WORD3

I tried the following, but obviously I'm missing something because that does not produce the desired results:

sed -i '' 's/WORD1.*WORD3/foo/g' file.txt

Upvotes: 40

Views: 95414

Answers (4)

Linux Pronto
Linux Pronto

Reputation: 56

The simplest answer to the initial question is:

Linux (GNU sed):

sed -i '/WORD1/, /WORD3/ s/WORD2/foo/' file.txt

MacOS (UNIX sed):

sed -i '' '/WORD1/, /WORD3/ s/WORD2/foo/' file.txt

Upvotes: 0

Rony
Rony

Reputation: 1734

content of a sample file.txt

$ cat file.txt 
WORD1 WORD2 WORD3
WORD4 WORD5 WORD6
WORD7 WORD8 WORD9

(Correction by @DennisWilliamson in comment)
$ sed -e 's/\([^ ]\+\) \+\([^ ]\+\) \+\(.*\)/\1 foo \3/' file.txt

WORD1 foo WORD3
WORD4 foo WORD6
WORD7 foo WORD9

while awk is somehow simpler

$ awk -F' ' '{ print $1" foo "$3 }' file.txt

WORD1 foo WORD3
WORD4 foo WORD6
WORD7 foo WORD9

Upvotes: 3

vyegorov
vyegorov

Reputation: 22845

sed -i 's/WORD1.*WORD3/WORD1 foo WORD3/g' file.txt

or

sed -i 's/(WORD1).*(WORD3)/\1 foo \2/g' file.txt

You might need to escape round brackets, depends on your sed variant.

Upvotes: 54

potong
potong

Reputation: 58351

This might work for you:

sed 's/\S\+/foo/2' file

or perhaps:

sed 's/[^[:space:]][^[:space:]]*/foo/2' file

If WORD1 and WORD3 occur more than once:

echo "WORD1 WORD2 WORD3 BLA BLA WORD1 WORD4 WORD3" |
sed 's/WORD3/\n&/g;s/\(WORD1\)[^\n]*\n/\1 foo /g'
WORD1 foo WORD3 BLA BLA WORD1 foo WORD3

Upvotes: 7

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