I am trying to read a variable value from test.sh and write it in file2.txt by replacing the word COMP in file2.txt
I am using below command to achieve this but not possible
sed -r 's/(echo "$NAME" test.sh)/COMP/' file2.txt
for your reference
test.sh contains
#!/bin/bash
NAME=RAJ
To read variables from a file you can use the source or . command. Then use double quotes to make the shell expand variables while preserving whitespace:
source test.sh && sed -i "s/$NAME/COMP/g" file2.txt
The BSD sed command takes the -i option but requires a suffix for the backup (but an empty suffix is permitted). So if you’re running on Mac or BSD system, use:
source test.sh && sed -i '' "s/$NAME/COMP/g" file2.txt
You've got your sed s/// backwards, I think. You want to search for COMP and replace the value of $NAME
. test.sh
sed "s/COMP/$NAME/" file2.txt
If $NAME can contain a slash character, it will break sed's s/// command, so you need to escape slashes in the variable expansion
. test.sh
replacement=${NAME//\//\\\/}
sed "s/COMP/$replacement/" file2.txt
# NAME='a/b/c/d'
# echo "${NAME//\//\\\/}" # => a\/b\/c\/d
