cut

cut options [files]
Cut out selected columns or fields from one or more files. In the following options, list is a sequence of integers. Use a comma between separate values, and a hyphen to specify a range (e.g., 1-10,15,20 or 50-). See also paste and join.

Options
-b list, --bytes list	Specify list of positions; only bytes in these positions will be printed.
-c list, --characters list	Cut the column positions identified in list. Column numbers start with 1.
-d c, --delimiter c	Use with -f to specify field delimiter as character c (default is tab); special characters (e.g., a space) must be quoted.
-f list, --fields list	Cut the fields identified in list.
-n	Don't split multibyte characters.
-s, --only-delimited	Use with -f to suppress lines without delimiters.
--output-delimiter=string	Use string as the output delimiter. By default, the output delimiter is the same as the input delimiter.
--help	Print help message and exit.
--version	Print version information and exit.

Examples
Extract usernames and real names from /etc/passwd:
cut -d: -f1,5 /etc/passwd

Find out who is logged on, but list only login names:
who | cut -d" " -f1

Cut characters in the fourth column of file, and paste them back as the first column in the same file:
cut -c4 file | paste - file