Question

I am trying to build a script that use "sed" to do the following :

• Search for files ending with .config (ie: test.js.config) in the current directory and all under it.
• Replace a string with another one (ie: {TEST} -> 50)
• Save the result in a new file that does not have the .config at the end (ex: test.js)
• Delete the original .config file (ie: test.js.config)

It would be great if it would be able to use another file that has the "string to search" with a "string to replace", like a dictionnary :

{TEST} = 50

{FIRST_NAME} = Alex

Answer 1

You can put a bunch of sed s/// commands in a file:

$ cat change.sed 
s/{TEST}/50/g
s/{FIRST_NAME}/Alex/g

If you have the following config input:
$ cat test.js.config
alert({TEST})
alert({FIRST_NAME})

The result will be:

$ sed -f change.sed test.js.config > test.js
$ cat test.js
alert(50)
alert(Alex)

The syntax is not great, but it is neither horrendous 🙂

OTOH, if you really want to use the bracket syntax in the replacing file…

$ cat test.js.config 
alert({TEST})
alert({FIRST_NAME})

… and the key-value pair in the replacement file…

$ cat change.txt 
TEST=50
FIRST_NAME=Alex

…you can write a sed command to change the key-value pair in sed replacements…

$ sed 's#\(.*\)=\(.*\)#s/{\1}/\2/g#' change.txt
s/{TEST}/50/g
s/{FIRST_NAME}/Alex/g

…and use this command in the real replacement:

$ sed "$(sed 's#\(.*\)=\(.*\)#s/{\1}/\2/g#' change.txt)" test.js.config > test.js
$ cat test.js
alert(50)
alert(Alex)