What is the best way to do string manipulation in a shell script?

Question

I have a path as a string in a shell-script, could be absolute or relative:

/usr/userName/config.cfg

or

../config.cfg

I want to extract the file name (part after the last /, so in this case: "config.cfg")

I figure the best way to do this is with some simple regex? Is this correct? Should or should I use sed or awk instead?

Shell-scripting's string manipulation features seem pretty primative by themselves, and appear very esoteric.

Any example solutions are also appreciated.

Answer 1

Instead of string manipulation I'd just use

file=`basename Filename`

Edit:

Thanks to unwind for some newer syntax for this (which assumes your filename is held in $filename):

file=$(basename $filename)

Answer 2

Most environments have access to perl and I'm more comfortable with that for most string manipulation.

But as mentioned, from something this simple, you can use basename.

Answer 3

If you're okay with using bash, you can use bash string expansions:

FILE="/path/to/file.example"
FILE_BASENAME="${FILE##*/}"

It's a little cryptic, but the braces start the variable expansion, and the double hash does a greedy removal of the specified glob pattern from the beginning of the string.

Double %% does the same thing from the end of a string, and a single percent or hash does a non-greedy removal.

Also, a simple replace construct is available too:

FILE=${FILE// /_}

would replace all spaces with underscores for instance.

A single slash again, is non-greedy.

Answer 4

I typically use sed with a simple regex, like this:

echo "/usr/userName/config.cfg" | sed -e 's+^.*/++'

result:

>echo "/usr/userName/config.cfg" | sed -e 's+^.*/++'
config.cfg