How to used "Unix built in Command in sed"

Question

I have file like below

127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
10.120.6.19 slatbnrduva00.ad.admin slatbnrduva00
#172.25.17.75 infrbaddc01.ad.lab

Where "slatbnrduva00" is my hostname. Now i am trying to delete that line using sed as below

sed -i '/`hostname`/d' myhost

but it is not deleting that line. Please let me know how to use built in linux command in sed

backtick is not special within single quotes, see https://stackoverflow.com/questions/7680504/sed-substitution-with-bash-variables and https://mywiki.wooledge.org/Quotes — Sundeep, Aug 09 '19 at 06:44
Possible duplicate of [Replace a string in shell script using a variable](https://stackoverflow.com/questions/3306007/replace-a-string-in-shell-script-using-a-variable) — Wiktor Stribiżew, Aug 09 '19 at 06:45

Jotne · Answer 1 · 2019-08-09T08:57:07.117

2

Unix built in commands need to be expanded.

You can do :

$(hostname)

or

`hostname`

But back-tics is old and deprecated.

To expand commands in sed, you need to use double quote ". With singel quote ' no expand.

So this should be the best why to do it:

sed -i "/$(hostname)/d" file

edited Aug 09 '19 at 08:57

answered Aug 09 '19 at 07:47

Jotne

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score 0 · Answer 2 · answered Aug 09 '19 at 09:04

Use grep:

grep -vFw "$(hostname -f)" file

-v reverse the match, which would effectively remove lines containing the hostname. -F will treat the search pattern as a fixed string rather than a regular expression. Meaning the . in the hostname means a literal ., not any character. -w matches at word boundaries meaning bar.baz.com would not match foobar.baz.com

How to used "Unix built in Command in sed"

2 Answers2