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sed - How to replace right part of equal sign (=) on a line

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# 1  
Old 12-25-2013
sed - How to replace right part of equal sign (=) on a line
Hello.

Using a bash script , I have a variable name for the file I want to modify
Code:
FILE_TO_EDIT="/etc/my_config_file"

And I have a variable name for the parameter to change
Code:
PARAMETER="fallback_node"
PARAMETER_NEW_VALUE="http://my_server_name.com/new_path"

A config file may contain :

1°) just and only just :
Code:
# fallback_node = http://example.com/path/to/sync

or 2°) just and only just :
Code:
fallback_node = http://my_server_name.com/some_web

In case 1 just add
Code:
"$PARAMETER = $PARAMETER_NEW_VALUE"

just under the commented line

In case 2
a) just replace the right part of the equal sign with $PARAMETER_NEW_VALUE
or
b) comment out the ligne and add a new ligne with. "$PARAMETER = $PARAMETER_NEW_VALUE"

Any help is welcome
# 2  
Old 12-25-2013
You could try this. Make sure the variables are sed-safe though..

Code:
sed "s;^[# ]*\(${PARAMETER} * = *\)\(.*\);# \1\2\n\1${PARAMETER_NEW_VALUE};" "${FILE_TO_EDIT}"

# 3  
Old 12-26-2013
Quote:
Originally Posted by neutronscott
You could try this. Make sure the variables are sed-safe though..

Code:
sed "s;^[# ]*\(${PARAMETER} * = *\)\(.*\);# \1\2\n\1${PARAMETER_NEW_VALUE};" "${FILE_TO_EDIT}"

Should be great if you can explain the syntax for my learning.

Any way I will try this.

---------- Post updated at 19:57 ---------- Previous update was at 14:00 ----------

Quote:
Originally Posted by neutronscott
You could try this. Make sure the variables are sed-safe though..

Code:
sed "s;^[# ]*\(${PARAMETER} * = *\)\(.*\);# \1\2\n\1${PARAMETER_NEW_VALUE};" "${FILE_TO_EDIT}"

Small bug.

Parameters :
Code:
PARAMETER="fallback_node"
PARAMETER_NEW_VALUE="http://localhost/FF_DB"

Initial data in config file :

Code:
[nodes]
# You must set this to your client-visible server URL.
# fallback_node = http://example.com/path/to/sync

Data after running sed command :

Code:
[nodes]
# You must set this to your client-visible server URL.
# fallback_node = http://example.com/path/to/sync
fallback_node = http://localhost/FF_DB

Good.
Now editing the config file with some other data and we get :

Code:
[nodes]
# You must set this to your client-visible server URL.
# fallback_node = http://example.com/path/to/sync
fallback_node = http://localhost/OTHER_TEST

Data after running sed command :

Code:
[nodes]
# You must set this to your client-visible server URL.
# fallback_node = http://example.com/path/to/sync
fallback_node = http://localhost/FF_DB
# fallback_node = http://localhost/OTHER_TEST
fallback_node = http://localhost/FF_DB

Something like :
1°) Add new line with new parameter after the 1st line which is commeted out when token is encounted
2°) comment out line with actual parameter the 1st line which is not commeted out when token is encounted
3°)1°) Add new line with new parameter after the next line which is commeted out when token is encounted

Any help is welcome
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