Question

Currently I’m trying to create a bash script for replacing new values I generated.

These values were stored in constants.php:

-----------constant.php : start-------------------
                      :
        define('PASS1', 'ABCD');
        define('PASS2', '1234');
                      :
-----------constant.php : end---------------------

After running script, (using sed) it should update the values of PASS1 and PASS 2 separately:

-----------constant.php : start-------------------
                      :
        define('PASS1', 'WXYZ');
        define('PASS2', '0987');
                      :
-----------constant.php : end---------------------

Is there a way I can find the KEY e.g. 'PASS1' and replace the values after the comma?

Answer 1

You can specify the occurrence with sed so sed "/PASS1/s/'[^']*'/'WXYZ'/2" matches any lines containing PASS1 and does the following substitution s/'[^']*'/'WXYZ'/2 which:

s/     # Substitute  
'      # Match a single quote
[^']*  # Match anything not a single quote 
'      # Match the closing single quote 
/      # Replace with 
'WXYZ' # The literal value
/2     # The 2 here matches the second quoted string, not the first.  

---

# First key 
$ sed "/PASS1/s/'[^']*'/'WXYZ'/2" file

        define('PASS1', 'WXYZ');
        define('PASS2', '1234');

# Second key
$ sed "/PASS2/s/'[^']*'/'0978'/2" file

        define('PASS1', 'ABCD');
        define('PASS2', '0978');

# In one go
$ sed "/PASS1/s/'[^']*'/'WXYZ'/2;/PASS2/s/'[^']*'/'0978'/2" file

        define('PASS1', 'WXYZ');
        define('PASS2', '0978');