read a file line by line to substitute a pattern

[biell]

I've got the same problem. I'd like to read a file line by line to substitute a pattern. The line gets splitted when the shell finds a space.

I'd like to do something like:

imagine the line "MP3Random On" inside a file called mp3_mod.conf
I'd like a script to be able to replace que word On for Off (or vice-versa)

for line in $(cat file); do
... do some grep test ...
done

Can anyone give me some help ?

Thank you very much.

Ok, got it figured out. I just needed to expand my toolset a bit.

One way for reading line by line:

awk '/./' some-text-file

[pavlo_7]

I'm not a programmer, but using anomie's "awk" example, I think you can do this:

cat file
MP3Random1 On
MP3Random2 Off
MP3Random3 On
MP3Random4 Off
MP3Random5 On

awk '/./' file | sed 's/On/Off/'

will give you:

MP3Random1 Off
MP3Random2 Off
MP3Random3 Off
MP3Random4 Off
MP3Random5 Off

[ghostdog74]

simplest case is like this

sed 's/On$/Off/' file

[eraker]

A little more specifically, sed can find that specific line and replace all instances of on with off for it.

for instance, the following

sed -e 's/\(MP3Random\) On/\1 Off/g' sample

seeks out and captures the "MP3Random" bit and then just reprints what was captured with "\1" and then prints something new after it.