CODEWITHSUNDEEP
sedcommentsconfiguration-files
Opux
Opux

Reputation: 788

Changing a configuration file and complex comment manipulation

I want to be able to change specific settings in a configuration file, which includes removing the comment code (;) that comment out those settings. Furthermore, I want to preserve real comments. That means that

some_setting=0

or

;some_setting=0

would both become

some_setting=9

But it also means that

some_setting=0    ;an honest-to-goodness comment

or

;some_setting=0    ;an honest-to-goodness comment

would be

some_setting=9    ;an honest-to-goodness comment

I'd also want to leave

;Idle talk about some_setting=

alone.

I seem to be able to achieve almost all of this with

sed -e 's/^\s*;\?\s*some_setting\s*=.*\(;\)\?/some_setting=9  \1/'

but the problem is the real comments get stripped out of lines that have some_setting. Notice that I've made allowances for there to be whitespace around a lot of these tokens.

I've looked at using awk for this, but it seems the best bet is sed.

I'm using GNU sed 4.2.2 on a Debian 8.3 for this.

Upvotes: 0

Views: 35

Answers (1)

Benjamin W.
Benjamin W.

Reputation: 52102

I used this as test input:

some_setting=0
;some_setting=0
some_setting=0    ;an honest-to-goodness comment
;some_setting=0    ;an honest-to-goodness comment
;Idle talk about some_setting=

Using this command:

$ sed -r 's/^;?(some_setting=)[^[:space:]]*(.*)/\19\2/' infile
some_setting=9
some_setting=9
some_setting=9    ;an honest-to-goodness comment
some_setting=9    ;an honest-to-goodness comment
;Idle talk about some_setting=

So a line starting with an optional ; followed by some_setting= and whatever non-space characters come after it is replaced with a line starting with some_setting=9; the rest of the line stays the same.

Upvotes: 1

Related Questions