Linux cat command - Display text files

Linux cat command: Display text files

Linux cat command Function Description

Use the cat command to display the contents of a text file, or to append the contents of several files to another file.

Linux cat command Syntax

cat [Option] [File]

The meaning of each option in the command is shown in the table:

Option	Description
-n	Numbering all rows of the output
-b	Numbering non-empty output lines
-s	When more than two consecutive blank lines are encountered, replace them with one blank line
-E	Show $ at the end of each line

Linux cat command Demo

Displays the contents of the /etc/grub.conf file:

[root@rhel ～]# cat /etc/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
#NOTICE: You have a/boot partition. This means that
#        all kernel and initrd paths are relative to/boot/, eg.
#        root(hd0,0)
#        kernel/vmlinuz-version ro root=/dev/sda2
#        initrd/initrd-[generic-]version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
password --encrypted
            61aFd0Gw3uB0r/oQE$y80vx6.tXQQdJTr457ORMUaqOuouP1wajM15vHjzvo4oI6sc P8HZfUwhrpKEAbOwDb4oUxmdwFDMcoJ59LMxH0
title Red Hat Enterprise Linux (2.6.32-358.el6.x86_64)
      root (hd0,0)
      kernel/vmlinuz-2.6.32-358.el6.x86_64 ro root=UUID=2ac36994-5a18-4741-8118-96fe2c57a6c6 r
d_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us rd_NO_MD crashkernel=auto LANG=zh_CN.UTF-8 rd_NO_LVM rd_NO_DM rhgb quiet
      initrd /initramfs-2.6.32-358.el6.x86_64.img

Enter the contents of textfile1 with line numbers into textfile2

[root@rhel ～]# cat -n textfile1 > textfile2

Append the contents of textfile1 and textfile2 with line numbers (blank lines are not added) to the file textfile3

[root@rhel ～]# cat -b textfile1 textfile2 >> textfile3

Display the /etc/passwd file with the $ symbol at the end of each line

[root@rhel ～]# cat -E /etc/passwd
root:x:0:0:root:/root:/bin/bashbin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologinadm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologinsync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdownhalt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologinuucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologingames:x:12:100:games:/usr/games:/sbin/nologin
gopher:x:13:30:gopher:/var/gopher:/sbin/nologinftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologindbus:x:81:81:System message bus:/:/sbin/nologin
........................

Use the cat command to create the mm.txt file

[root@rhel ～]# cat >mm.txt<<EOF
>Hello                    //Enter the character Hello here
>Linux                   //Enter the character Linux here
>EOF                    //Enter the character EOF here and it will automatically return to the Shell prompt screen