Simple string manipulations

[Simon King]

Often, you need to modify a string (such as a filename or a path) in the shell. Here are some useful ways to do that.

The basename command strips prefixes and suffixes from strings like this:

$ basename path/to/some_file.txt
some_file.txt

$ basename some_file.txt
some_file.txt

$ basename some_file.txt .txt
some_file

[Simon King]

You might need to cut a string on a separator, keeping only some parts if it. There are lots of ways to do that. The built-in cut command is one way (and you can pass it files too, whereby it will perform the same operation to all lines). The pipe “|” sends the output of one process to the input of the next.

$ # -c cuts using character positions
$ echo some_file.txt | cut -c6-9
file

$ # -d cuts using the delimiter you specify
$ echo some_file.txt | cut -d"_" -f1
some

$ # and -f specifies which field(s) you want to keep
$ echo some_file.txt | cut -d"_" -f2
file.txt

$ echo a_long_file_name.txt | cut -d"_" -f2-4
long_file_name.txt

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