light

Get the current backlight value in percent

$ light

$ light -S [50]

$ light -U [20]

$ light -A [20]

cat [OPTION]... [FILE]...

-A, --show-all
    Equivalent to -vET.

-b, --number-nonblank
    Number the non-blank output lines, starting at 1.

-e
    Equivalent to -vE.

-E, --show-ends
    Display $ at end of each line.

-n, --number
    Number all output lines, starting at 1.

-s, --squeeze-blank
    Suppress repeated empty output lines.

-t
    Equivalent to -vT.

-T, --show-tabs
    Display TAB characters as ^I.

-u
    (ignored)

-v, --show-nonprinting
    Use ^ and M- notation, except for LFD and TAB.

--help
    Display help message and exit.

--version
    Output version information and exit.

FILE
    The file(s) to be concatenated and printed to standard output.

The cat command is a fundamental Linux utility used to concatenate files and print them to standard output. Its primary function is to display the contents of one or more files on the terminal. It can also be used to create, append to, or overwrite files, although these uses are less common and potentially dangerous due to risk of accidental data loss. cat is often used in conjunction with other commands through piping (|) to perform more complex operations, such as filtering, searching, and sorting text within files.
Because cat is a base command it can usually be found as a busybox implementation even in minimal linux system where other more specific commands might be absent. It's a versatile tool for quick file inspection and basic text manipulation. Its simplicity makes it easy to learn and use, while its ubiquity ensures it's available on virtually any Linux distribution.

Using cat to concatenate large files can consume significant system resources. Redirecting the output of cat to one of its input files can result in data loss.

If no FILE is specified, or if FILE is '-', cat reads from standard input.

The cat command will exit with one of the following values:
0: No errors occurred.
>0: An error occurred.

The cat command has been a part of Unix since its earliest versions. It's a core utility that has remained relatively unchanged over the decades, reflecting its fundamental importance in text processing. It has continued in GNU and BSD distributions and is expected in every POSIX compliant system.

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