Linux cat command

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The cat (full English name: concatenate) command is used to concatenate files and print them to the standard output device.

Usage rights

All users

Syntax format

cat [-AbeEnstTuv] [--help] [--version] fileName

Parameter description:

-n or --numberBy 1 Start numbering all output lines.

-b or --number-nonblankAnd -n Similar, but not numbered for blank lines.

-s or --squeeze-blankWhen encountering more than two consecutive blank lines, replace them with a single blank line.

-v or --show-nonprinting: Use ^ and M- : Symbols, except LFD and TAB.

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

-T or --show-tabs: Display the TAB character as ^I.

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

-e:Is equivalent to-vE"option;

-t:Is equivalent to-vT"option;

Example:

Copy textfile1 Add line numbers to the document content and input textfile2 This document contains:

cat　-n textfile1　> textfile2

Copy textfile1 and textfile2 Add line numbers to the document content (blank lines are not added) and then append the content to textfile3 In the document:

cat　-b textfile1　textfile2　>> textfile3

Clear /etc/Content of test.txt document:

cat　/dev/null >　/etc/test.txt

cat can also be used to create image files. For example, to create a floppy disk image file, after placing the floppy disk, input:

cat　/dev/fd0 > OUTFILE

On the contrary, if you want to write the image file to a floppy disk, input:

cat IMG_FILE >　/dev/fd0

Note:

• 1OUTFILE refers to the output image filename.

• 2IMG_FILE refers to the image file.

• 3When writing back to device from the image file, the device capacity needs to be equivalent.

• 4Used to make bootable disks usually.

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