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Old 09-14-2021, 04:36 AM   #1
angel115
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Regex - Modify Parameter in config file


Hi There,

I'd like to modify a parameter in a config file using a regex
Sample config file:
Code:
[ServiceXY]
ParamXY=true
Enable=False

[Service123]
ParamXY=true
Enable=False

[Service345]
ParamXY=true
Enable=False

[Service456]
ParamXY=true
Enable=False
My goal is to modify the "Enable=False" of the section "Service345" to "Enable=True"

The following work fine in Regex101.com
Match
Code:
/(\[Service345\]\r?\n.*(\r?\n([^[\r\n].*)?)*Enable=)False/
And use this as substitution
Code:
/$1True/

But when I try to use it in command line it doesn't work:
Code:
perl -pe 's/(\[Service345\]\r?\n.*(\r?\n([^[\r\n].*)?)*Enable=)False/\1/gm' test.conf
Any Idea why it doesn't substitute in command line?

Thanks for your help.

Last edited by angel115; 09-14-2021 at 05:39 AM. Reason: Fix Mistake
 
Old 09-14-2021, 04:43 AM   #2
pan64
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the name of the section is Service345 or Section345 ?
 
Old 09-14-2021, 05:22 AM   #3
syg00
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Probably easier done - and more readable - in awk or sed. Might help debugging errors too.
 
Old 09-14-2021, 05:40 AM   #4
angel115
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Quote:
Originally Posted by pan64 View Post
the name of the section is Service345 or Section345 ?
Service, I just fix it in the original post
 
Old 09-14-2021, 05:43 AM   #5
angel115
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Quote:
Originally Posted by syg00 View Post
Probably easier done - and more readable - in awk or sed. Might help debugging errors too.
I've tried as well with sed but got the same result.
sed -E 's/(\[Service345\]\r?\n.*(\r?\n([^[\r\n].*)?)*Enable=)False/\1True/gm' test.conf
 
Old 09-14-2021, 05:47 AM   #6
pan64
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using sed you can do something like this:
Code:
sed '/Service345/,/^[[]/s/Enable=False/Enable=True/' file
 
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Old 09-14-2021, 05:53 AM   #7
syg00
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Or even this if you can assure the linecount
Code:
sed '/\[Service345\]/{N;N;s/False$/True/}' file

Last edited by syg00; 09-14-2021 at 05:57 AM. Reason: typo
 
Old 09-14-2021, 06:20 AM   #8
Turbocapitalist
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Quote:
Originally Posted by angel115 View Post
Any Idea why it doesn't substitute in command line?
It's still reading one line at a time, using newlines or whatever for the line separators. Try clearing the input record separator or else assigning it to null or something strange:

Code:
perl -0 -p -e 's/^(\[Service345\][\r\n\s\w=]*)Enable=False/$1Enable=True/m' test.conf
perl -0777 -p -e 's/^(\[Service345\][\r\n\s\w=]*)Enable=False/$1Enable=True/m' test.conf

perl -p -e 'undef $/; s/^(\[Service345\][\r\n\s\w=]*)Enable=False/$1Enable=True/m' test.conf
See "man perlrun" and "man perlvar". The former for -0 and the latter for $INPUT_RECORD_SEPARATOR aka $RS aka $/

Edit:

Code:
perl -p -e 'BEGIN{ $/=qq(\n\n);} s/^(\[Service345\][\r\n\s\w=]*)Enable=False/$1Enable=True/m'  test.conf
and so on ...

Last edited by Turbocapitalist; 09-14-2021 at 06:34 AM. Reason: g not needed
 
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Old 09-14-2021, 06:25 AM   #9
syg00
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Now, about that readability ...
 
Old 09-14-2021, 06:32 AM   #10
boughtonp
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Quote:
Originally Posted by angel115 View Post
But when I try to use it in command line it doesn't work:
Code:
perl -pe 's/(\[Service345\]\r?\n.*(\r?\n([^[\r\n].*)?)*Enable=)False/\1/gm' test.conf
Any Idea why it doesn't substitute in command line?
The answer to the question you've asked is that you're trying to use a multi-line pattern but are splitting the input on newlines.

In Perl you can use -0 (that's zero, not O) to change the delimiters to ASCII NUL character instead of newline, and thus treat the entire input as a single record.

Adding that would make your pattern work, but I recommend removing/ignoring carriage returns to simplify things, and being either more flexible with your non-relevant lines, or more explicit. Also, you were missing the ^$ bounds that make the m flag useful, and only need g flag if there could be multiple instances to replace, so...

Code:
perl -p0e 's/(^\[Service345\](?:\n(?!\[).*)*?\nEnable=)False$/\1True/m' input.config
Code:
perl -p0e 's/(^\[Service345\]\nParamXY=.*\nEnable=)False$/\1True/m' input.config

If doing this with sed, a corrected version of Pan's expression would be:
Code:
sed '/^\[Service345\]/,/^[[]/s/^Enable=False$/Enable=True/' file

Last edited by boughtonp; 09-14-2021 at 06:39 AM.
 
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Old 09-15-2021, 12:51 AM   #11
chrism01
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Assuming that this is not a one-off, and going with syg00's comment about 'readability', which I totally agree with, frankly I'd actually write a short Perl program instead.
The result would be much more readable / maintainable.
 
Old 09-15-2021, 01:41 PM   #12
MadeInGermany
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Code:
awk '
  BEGIN {FS=OFS="="}
  f && $1=="Enable" {$2="True"}
  /\[/ {f=0}
  /\[Service345\]/ {f=1}
' file
 
  


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