Using sed or awk to update a line

Question

I want to open the httpd.conf file and change the LogFormat line with the new parameters. The criterion will be that the line should start with "LogFormat" and end with the word "combined"

Here is how I do manually. I want to change the line programatically.

vi /etc/httpd/conf/httpd.conf 
#LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined
LogFormat "\"%h\" \"%l\" \"%u\" \"%{%Y-%m-%d %H:%M:%S}t\" \"%r\" \"%>s\" \"%b\" \"%{Referer}i\" \"%{User-Agent}i\" \"%D\" \"%T\" \"%q\" \"%f\" \"%v\" " combined

Answer 1

You could try something like:

sed 's/^LogFormat.*combined$/new-logformat-line-whatever/' httpd.conf

Answer 2

Use Perl instead, with its -i (inplace-edit) flag.

perl -i.bak -pe 's/^LogFormat (.*) combined$/replacement/' httpd.conf

This will modify the file httpd.conf in place, storing a backup in the file "httpd.conf.bak". Replace "replacement" with the actual replacement text you want.

Answer 3

#!/bin/bash

cp /etc/httpd/conf/httpd.conf  /etc/httpd/conf/httpd.conf.bak
awk 'BEGIN{
 pat1="\\\"%{%Y-%m-%d %H:%M:%S}t\\\""
 pat2="\\\"%D\\\" \\\"%T\\\" \\\"%q\\\" \\\"%f\\\" \\\"%v\\\""
}
/^LogFormat.*combined/{
 $5=pat1
 $NF=pat2"\042 combined"
}1' file >temp
mv temp /etc/httpd/conf/httpd.conf