cat

cat [-n] [-A] [-b] [-s] [file...]

cat (concatenate) reads files sequentially and writes their contents to standard output. It is one of the most frequently used Unix utilities, serving as the standard way to display file contents, combine multiple files, and pipe data to other commands in shell pipelines.When given multiple file arguments, cat concatenates them in order, making it useful for joining split files or appending content. With no file arguments or a dash (-), it reads from standard input, which allows it to function as a simple pass-through in pipelines. Various flags control output formatting, including line numbering and display of non-printing characters.

-n, --number

Number all output lines

Number non-blank output lines only

Suppress repeated empty output lines

Equivalent to -vET; show all characters

Display $ at end of each line

Display TAB characters as ^I

Use ^ and M- notation for non-printing characters

Equivalent to -vE

Equivalent to -vT

For large files, consider using less or head/tail instead. Using cat to pipe a single file to another command (UUOC - Useless Use of Cat) is often unnecessary.

Part of GNU Coreutils. Originated in 1971 for first Edition Unix by Ken Thompson at Bell Labs. One of the oldest and most fundamental Unix utilities.

less(1), more(1), head(1), tail(1), tac(1)

Source code · Documentation