replace first instance(not first instance in line)

Shell Programming and Scripting
1

Alright, I think I know what I am doing with sed(which probably means I don't). But I cant figure out how to replace just the first occurance of a string. I have tried sed, ed, and grep but can't seem to figure it out. If you have any suggestions I am open to anything!

2

By "first occurance" do you mean first occurance in a line or first occurance in a file?

3

Assuming it is the first occurance in a file, the following example should show you how to
do what you want to do using awk.

$ cat file
true line1
true line2
$ awk '/true/ && n == 0 { sub(/true/,"false"); ++n } { print }' file
false line1
true line2
$
4

You are awsome, THANKS!