I have the below lines in a file:


How can i create a sed line to match pattern SUT_INST_EXAMPLES & SUT_INST_PING and set false to true?

I can't simply replace false with true because I don't want to change SUT_INST_PIT & SUT_INST_TICS even if they are false!!!

I have at the moment two sed commands that are working, but i would like one line only!

sed -i "s/SUT_INST_EXAMPLES=false/SUT_INST_EXAMPLES=true/g" <file>
sed -i "s/SUT_INST_PING=false/SUT_INST_PING=true/g" <file>

One more thing the sed line should be able to be parametrized to set false->true or true->false, but only for SUT_INST_EXAMPLES & SUT_INST_PING.

Solution (according to @RomanPerekhrest) and how to use it in send (expect script):

send "sed -i 's\/^\\(SUT_INST_EXAMPLES\\|SUT_INST_PING\\)=false\/\\1=true\/' file\r"

sed approach:

sed -i 's/^\(SUT_INST_EXAMPLES\|SUT_INST_PING\)=false/\1=true/' file

file contents:


\(SUT_INST_EXAMPLES\|SUT_INST_PING\) - alternation group, matches either SUT_INST_EXAMPLES OR SUT_INST_PING at the start of the string

Alternative gawk(GNU awk) approach:

gawk -i inplace -F'=' -v OFS='=' '$1~/^SUT_INST_(EXAMPLES|PING)/{$2=($2=="false")? "true":"false"}1' file
  • I am trying to use the sed line from your answer in a expect send command but it is failing: SUT:/home # =true/' file -i 's/^(SUT_INST_EXAMPLES|SUT_INST_PING)=false/ -bash: syntax error near unexpected token SUT_INST_EXAMPLES – FotisK May 9 '17 at 21:04
  • Updated Question with solution according to @RomanPerekhrest. – FotisK May 10 '17 at 18:06

You can simply toggle with:

sed -i -E '/^SUT_INST_(PING|EXAMPLES)=/{s/false/true/;t;s/true/false/;}' infile

This will change true to false or false to true depending on the current value.


sed allows you to do multiple operations on each line:

sed -e '...' -e '...' file

So you can at least combine your two sed invocations into one with

sed -i -e 's/^SUT_INST_EXAMPLES=false/SUT_INST_EXAMPLES=true/' \
       -e 's/^SUT_INST_PING=false/SUT_INST_PING=true/' file

To parametrize the replacement, use variables:


sed -i -e "s/^SUT_INST_EXAMPLES=.*\$/SUT_INST_EXAMPLES=$examples/" \
       -e "s/^SUT_INST_PING=.*\$/SUT_INST_PING=$ping/" file

The above will unconditionally set the values of SUT_INST_EXAMPLES and SUT_INST_EXAMPLES to that of $examples and $ping respectively.

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