nixCraft

Hey guys, i am about to throw it all in because i just cannot get this to work :S.
I am currently using fedora core 3.

All i wanted to do is search through a file and find a string and replace with an argument from the command line.

So basically i have a file which has the contents of :

this is a test file
yes i am cool

say if i want to replace cool with $1 (which is 'crap', an argument from the shell) how do i accomplish this?

So far i have $1 = awk '/yes/ { print $4 }' file > file

I then want to overwrite the file with the updated contents. So the contents of file look like this:

this is a test file
yes i am crap

This just doesnt seem to do the job. If anyone knows please help!! i wont have any fingernails left soon :P thanks guys.

I’m not sure whether you are using correct tool or not… IMPO you should try sed which has syntax like :

's/TEXT-TO-FIND/REPLACE-TEXT /g'


So to replace text in file i.e. cool with crap
This should solve your problem… now you can write small script to do rest of work

Yeah thanks for your reply. I was thinking about using sed the other night and found out it was far easier to do what i was after than awk. However i have run into another problem.

How do i replace for example:

BIAS UD=34 UG=20

so if i wanna replace UG=20 with UG=30 i can use sed 's/UG=20/UG=30/'' ...easy.

But i am incrementing a UG from the command line so i need to change the UG occurrence already in the file with my new one ...eg:

INC=40

sed 's/UG=*/UG='$INC'/' i need to be able to change UG=* in the file where star is any value...is there anyway to take star as wildcard instead of literally? sorry for my poor english. Its hard to explain my problem.

Few days back i had read something as follows posted by vivek (old forum) which basically changes the values of the config file

Save file and Execute

It will create /etc/test.config as follows
host='me.test.com'
ip=''

Again if you modify the script file with test data
host='YOU.test.com'

And script executed now output will be changed to as follows
host='YOU.test.com'
ip=''"

Try this one or may be we can play more with sed .... later ..

Thanks once again for your help. That is another way to accomplish the problem that i was having. However i have worked out a simple solution.

Where i was trying to substitute UG=* with UG="$INC" etc.....within shell i found you can use .* for all occurrences so i used UG=.*/UG="$INC" and presto....she works

I have finally got the program working 100 % with error checking. thanks heaps