Master the Linux cat Command: Options, Syntax, and Real-World Examples

cat command is used to concatenate files and print them to standard output.

Usage permissions

All users

Syntax format

cat [options] fileName

Parameter description

-n or --number : number all output lines starting from 1.

-b or --number-nonblank : number non-blank lines only.

-s or --squeeze-blank : replace multiple consecutive blank lines with a single blank line.

-v or --show-nonprinting : display non-printing characters (except LFD and TAB) using ^ and M- notation.

-E or --show-ends : display $ at end of each line.

-T or --show-tabs : display TAB characters as ^I.

-e : equivalent to -vE.

-A , --show-all : equivalent to -vET.

-t : equivalent to -vT.

Examples

Add line numbers to textfile1 and write to textfile2: cat -n textfile1 > textfile2 Append numbered contents of textfile1 and textfile2 (excluding blank lines) to textfile3: cat -b textfile1 textfile2 >> textfile3 Clear the contents of /etc/test.txt: cat /dev/null > /etc/test.txt Create a floppy disk image from the device: cat /dev/fd0 > OUTFILE Write an image file back to the floppy device: cat IMG_FILE > /dev/fd0 OUTFILE is the name of the output image file.

IMG_FILE is the source image file.

The device capacity must match when writing back.

Commonly used for creating bootable floppy disks.