List of All Bash External Variables

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List of All Bash External Variables

In last article, we discussed out Bash Environment Variables which always play an important role in Bash Shell Scripting and here in this article, we listed out all Bash External Variables which you can use while doing Bash Programming.

External programs are often used within shell scripts; there are a few builtin commands ( echo , which , and test are commonly builtin), but many useful commands are actually Unix utilities, such as tr , grep , expr and cut . The backtick (`)is also often associated with external commands.

bzip2	Compression using the Burrows-Wheeler block sorting text compression algorithm and Huffman coding.
cat	List the contents of the specified file.
chage	Change the password expiration date for the specified system user account.
chfn	Change the specified user account’s comment information.
chgrp	Change the default group of the specified file or directory.
chmod	Change system security permissions for the specified file or directory.
chown	Change the default owner of the specified file or directory.
chpasswd	Reads a file of login name and password pairs and updates the passwords.
chsh	Change the specified user account’s default shell.
compress	Original Unix file compression utility.
cp	Copy the specified files to an alternate location.
df	Display current disk space statistics for all mounted devices.
du	Display disk usage statistics for the specified filepath.
file	View the file type of the specified file.
finger	Display information about user accounts on the Linux system or a remote system.
grep	Search a file for the specified text string.
groupadd	Create a new system group.
groupmod	Modify an existing system group.
gzip	The GNU Project’s compression using Lempel-Ziv compression.
head	Display the first portion of the specified file’s contents.
killall	Send a system signal to a running process based on process name.
less	Advanced viewing of file contents.
link	Create a link to a file using an alias name.
ls	List directory contents.
mkdir	Create the specified directory under the current directory.
more	List the contents of the specified file, pausing after each screen of data.
mount	Display or mount disk devices into the virtual file system.
passwd	Change the password for a system user account.
ps	Display information about the running processes on the system.
pwd	Display the current directory.
mv	Rename a file.
rm	Delete the specified file.
rmdir	Delete the specified directory.
sort	Organize data in a data file based on the specified order.
stat	View the file statistics of the specified file.
tail	Display the last portion of the specified file’s contents.
tar	Archive data and directories into a single file.
touch	Create a new empty file, or update the timestamp on an existing file.
umount	Remove a mounted disk device from the virtual file system.
useradd	Create a new system user account.
userdel	Remove an existing system user account.
usermod	Modify an existing system user account.
zip	Unix version of the Windows PKZIP program.