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I have a file that contains lines like this
proto udp
.
.
.
..
server 10.10.8.0/24 255.255.255.0
I need a way to remove only /24 from this line server 10.10.8.0/24 255.255.255.0 to become
server 10.10.8.0 255.255.255.0
considering that this line is variable but the only constant thing is the / it may be like this
server 198.196.178.0/8 255.0.0.0
so I need a way to remove only /8 from this line to become like this
server 198.196.178.0 255.0.0.0
Using GNU sed with captured groups:
sed -r 's_^(server\s+([^.]+.){3}[0-9]{1,3})/[0-9]+(.*)_\1\3_' file.txt
To edit the file in place, use -i option:
sed -ri 's_^(server\s+([^.]+.){3}[0-9]{1,3})/[0-9]+(.*)_\1\3_' file.txt
Example:
% sed -r 's_^(server\s+([^.]+.){3}[0-9]{1,3})/[0-9]+(.*)_\1\3_' <<<'server 10.10.8.0/24 255.255.255.0'
server 10.10.8.0 255.255.255.0
% sed -r 's_^(server\s+([^.]+.){3}[0-9]{1,3})/[0-9]+(.*)_\1\3_' <<<'server 198.196.178.0/8 255.0.0.0'
server 198.196.178.0 255.0.0.0
sed -i you should keep in mind two things: (1) For beginners, stress that they test the command without the -i switch or they may cause damage hard to reverse. (2) BSD sed has a -i switch but requires a backup extension, even if it's an empty string (i.e. ''). When this is omitted the command is interpreted as the backup extension, and the filename following it is parsed as a sed command (usually leading to errors). To avoid nasty surprises and for better portability with -i, always include a backup extension even if only ''.
sed, the backup extension has to be stuck to -i which means you can't use -i ''. -i.bak is portable between GNU and BSDs, but neither -i (same as -i'') nor -i '' are.
Mar 16, 2016 at 10:35
sed '/^server/s|/[0-9]*||'may be enough for your need.