This can be accomplished by using the sed command.
sed = stream editor for filtering and transforming text
For this example we will have a file called test.txt that contains the following text “This is a test file with some test information, containing some test data.“
We want to replace all instances of test in the file with cool and save the output to a new file called cool.txt
To accomplish this open a new command line window and type and execute the following command:
sed -e 's/test/cool/g' test.txt > cool.txt
-e = add the script to the commands to be executed
s = s/regexp/replacement/
Attempt to match regexp against the pattern space. If success‐
ful, replace that portion matched with replacement. The
replacement may contain the special character & to refer to that
portion of the pattern space which matched, and the special
escapes \1 through \9 to refer to the corresponding matching
sub-expressions in the regexp.
g = Copy/append hold space to pattern space.
If you view cool.txt by using the cat command
you’ll see the following output
This is a cool file with some cool information, containing some cool data.
To learn more about the set command type in man sed in the command line