2014-02-16

A-Z Of Bash Commands For Bash Learner

බොහෝ වැදගත් වන ලිනකස් කමාන්ඩ්ස් 

A
alias: If creating an alias is what you want, then this is it.
apropos: We’re not the only ones providing help. This command you to search through the Help manual pages.
apt-get: This one works on Debian and Ubuntu distros. It is used to install and search for software packages.
aptitude: See the similarity with the above command? This one does the same thing.
aspell: Got bad spellings? Use the spell checker.
awk:No, this command is not for awkward situations. It lets you find text and replace it. Also, you can sort, index and validate things in a database.

B
basename: Sometimes files and directories have suffixes to their names. This one strips them off it.
bash: GNU Bourne-Again Shell
bc: This command is an arbitrary precision calculator language 
bg: bg could stand for background couldn’t it? Regardless, that’s what it does, sends to the background
break: Exit from a loop
builtin: Run a shell builtin
bzip2: When there’s ‘zip’ in the name, that’s what it does. It compresses or decompresses files that are named.

C
cal: Need a calendar? This command displays one.
case: In ‘case’ you want to perform a command conditionally. This is how to do it.
cat: In programming, ‘cat’ usually stands for concatenate. Here too, but this command displays the content of the files after concatenation.
cd: Change Directory
cfdisk: In Linux, this command is the partition table manipulator
chgrp: This is how you change the ownership of a group.
chmod:‘Ch’ is for change. This one changes the access permissions.
chown: This one sounds too much like clown! Anyway, it’s not funny though. It changes the owner and group of a file.
chroot: Using this you can run a command, but with a different root directory
chkconfig System services (runlevel)
cksum: It displays the CRC checksum ad byte counts.
clear: If you need to clear the terminal screen, use this command.
cmp: Compare two files
comm: Compare two sorted files line by line
command: Run a command - ignoring shell functions
continue: This is for resuming the next iteration of a particular loop.
cp: Make a copy of files to a different location.
cron: Daemon to execute scheduled commands
crontab: Scheduling is sometimes very important. This command does it, it schedules a command that will run at a specified time.
csplit: Split a file into context-determined pieces
cut: When you need to cut down a file into parts, this is the command to use.

D

date: Use this command to change the date and time.
dc: The command stands for Desk Calculator.
ddrescue: Like most other such commands, this is the disk recovery tool.
declare: This command is used to declare the variables and to give attributes.
df: When you want to know the free space on your disk, use this.
diff: This command prints the differences between two files.
diff3: This is the same command as the previous one, but for three files.
dig: Need to lookup the DNS? Use this.
dir: Use this command for listing directory contents briefly.
dircolors: This command is used for colour setup for the ‘ls’ command.
dirname: Use this command to change a full pathname into just a path.
dirs: This command shows you the list of directories that are remembered.
dmesg: Use this command when you want to print kernel and driver messages.
du: Use this command to get an estimation of the file space usage.

E

echo: This command is used for displaying message on the screen.
egrep: This searches for files that have lines matching an extended expression.
eject: Use this when you need to eject a removable media.
enable: Use this to disable or enable bulletin shell commands.
env: Environment variables
ethtool: Ethernet card settings
eval: This command is used when you need to evaluate a many commands.
exec: For executing a command.
exit: Exiting the shell.
expand: This command converts all the tabs to spaces.
export: This command sets an environment variable.
expr: Some evaluate commands, this evaluates expressions.

F

false: Do nothing, unsuccessfully
fdformat: This command is used for low level format of a floppy disk.
fdisk: This is a partition table manipulator for Linux systems.
fg: This command is used for sending a task to the foreground.
fgrep: Use this command to search through files for tasks that match a string.
file: This is used to determine the file type.
find: This is used to find files that match a desired criteria.
fmt: This is used for reformatting paragraph text.
fold: The name is quite suggestive, it wraps text in order to fit a certain width.
format: This simply formats tapes or disks.
free: Use this to see the memory usage.
fsck: This is used for checking the consistency of the file system and repair it.
fuser: This command identifies and kills the process accessing a file.

G

gawk: This command is used to find text within files and replace it.
getopts: Parse positional parameters
grep: Through this you can search in files for lines matching a certain pattern.
groupadd: Use this command to add security user groups.
groupdel: This one is used for deleting a certain group.
groupmod: While the last one deletes, this one modified a group.
groups: Print the names of groups in which an user is located.
gzip: This command is used for compressing and decompressing files.

H

hash: This command is used to refer to the complete pathname of a name argument.
head: Use this for output for the first part of files.
help: Display the built in help for a command.
history: Command History
hostname: Print or set system name

I

iconv: Use this to convert the character set in files.
id: Display the group ids or user ids.
if: Conditional command.
ifconfig: Used to configure network interfaces.
ifdown: Use this command for stopping a network interface. 
ifup: Start a network interface app with this command.
import: Used for the X server. Capture a screen and save image.
Install: Set attributes and copy files

J

jobs: Use this for listing jobs that are active.
Join: This one joins lines, which are on a common field.

K

kill: Stops a process from running.
Killall: Kills the processes by name.

L

less: This command displays the output on a single screen at a time.
let: This is for doing arithmetic on shell variables.
link: This command is used for creating a link to another file. 
ln: This one creates a symbolic link to another file.
local: Use this for creating variables.
locate: This one is used for finding files.
logname: This is used to print the login name being used currently.
logout: Use this command to exit a login shell.
look: When you just want to see lines that start with a particular string.
lpc: It stands for Line Printer Control.
lpr: This is for offline print.
lprint: Use this command to print a file.
lprintd: Use this to abort an ongoing print job.
lprintq: This command lists the print queue.
lprm: This removes the jobs from the print queue.

M

make: This command is used for recompiling the group of programs. 
man: This is short for manual and provides help on a command.
mkdir: Creating directories.
mkfifo: Use this to make FIFOs.
mknod: This is to create character special files or block files.
more: This displays the output, but in a single screen at a time.
mount: Used for mounting a particular filesystem.
mtools: Manipulating files from MS-DOS.
mtr: Network diagnostics command for things like ping and traceroute.
mv: Used for moving and renaming files and directories.
mmv: Mass Move and Rename

N

netstat: Get information on networking.
nice: Use this to set the priority of a job or a command.
nl: Write files and number lines.
nohup: This one runs a command, which is not affected by hangups.
notify-send: This command sends desktop notifications.
nslookup: This command is used to query internet name servers interactively.

O

open: This command opens a file in its default application.
op: Use this command for gaining operator access.

L

less: This command displays the output on a single screen at a time.
let: This is for doing arithmetic on shell variables.
link: This command is used for creating a link to another file. 
ln: This one creates a symbolic link to another file.
local: Use this for creating variables.
locate: This one is used for finding files.
logname: This is used to print the login name being used currently.
logout: Use this command to exit a login shell.
look: When you just want to see lines that start with a particular string.
lpc: It stands for Line Printer Control.
lpr: This is for offline print.
lprint: Use this command to print a file.
lprintd: Use this to abort an ongoing print job.
lprintq: This command lists the print queue.
lprm: This removes the jobs from the print queue.

M

make: This command is used for recompiling the group of programs. 
man: This is short for manual and provides help on a command.
mkdir: Creating directories.
mkfifo: Use this to make FIFOs.
mknod: This is to create character special files or block files.
more: This displays the output, but in a single screen at a time.
mount: Used for mounting a particular filesystem.
mtools: Manipulating files from MS-DOS.
mtr: Network diagnostics command for things like ping and traceroute.
mv: Used for moving and renaming files and directories.
mmv: Mass Move and Rename

N

netstat: Get information on networking.
nice: Use this to set the priority of a job or a command.
nl: Write files and number lines.
nohup: This one runs a command, which is not affected by hangups.
notify-send: This command sends desktop notifications.
nslookup: This command is used to query internet name servers interactively.

O

open: This command opens a file in its default application.
op: Use this command for gaining operator access.

P

passwd: Use this command to modify user passwords.
paste: This command is used for merging lines in files.
pathchk: It is used to check the portability of a file name.
ping: This command is used for testing network connections.
pkill: This command stops processes from running.
popd: This command restores the previous value of the directory you’re currently in.
pr: Prepare your files for printing using this.
printcap: Printer capability database
printenv: Print environment variables
printf: This command is used for formatting and printing data.
ps: This stands for Process Status.
pushd: Change the directory and save it first.
pwd: It stands for Print Working Directory.

Q

quota: This command displays the disk usage and its limits.
quotacheck: This commands lets you scan a file system to find its disk usage.
quotactl: This is used to set disk quotas.

R

ram: Ram disk device
rcp: When using two machines, this command copies files between them.
read: This commands is used for reading a line from standard input.
readarray: This commands reads from stdin into an array variable.
readonly: This command marks the variables and functions as readonly.
reboot: Self explanatory, use this command to reboot your system.
rename: Rename files
renice: This command alters the priority of the processes running. 
remsync: This command synchronises remote files through email.
return: This is used to exit from a shell function.
rev: This command reverses the lines in a file.
rm: Use this to remove particular files.
rmdir: Same as above, but for directories.
rsync: This is for synchronising file trees.

S

screen: Use this to run remote shells using ssh.
scp: This is used to create a secure copy.
sdiff: This command is used to merge two files in a secure manner.
sed: This is for the stream editor.
select: This is used when you need to accept keyboard inputs.
seq: This command is used for printing numeric sequences.
set: This command lets you manipulate shell functions and variables.
sftp: Run the secure file transfer program using this.
shift: This command is used for shifting positional parameters.
shopt: Shopt stands for Shell Options.
shutdown: Use this command when you want to shutdown Linux or restart it.
sleep: Add a delay using this command.
slocate: This is used to find particular files.
sort: Text files are sorted using this.
source: This command is used for running commands from a file.
split: This command is used to break a file into fixed sizes.
ssh: This is used to run the remote login program, that is, the secure shell client.
strace: This is used to trace signals and system calls.
su: Substitute the user identity using this command.
sudo: This is used for executing commands as a different user.
sum: File cheksums are printed using this command.
suspend: This command is used to suspend the execution of the current shell.
sync: This command is used in order to synchronise data from a disk with the memory.

T
tail: Use this command when you want to output only the last part of a file.
tar: This command is used in order to store a list or extract files in an archive.
tee: This command is used for redirecting output into multiple files.
test: This command is used for evaluating conditional expressions.
time: The running time of a program can be measured using this command.
timeout: This command is used to put a time limit on a command.
times: Use this to find the user and system times.
touch: Timestamps on a file can be changed using this.
top: This is used to get a list of the processes that are running on the system.
traceroute: Use this command to Trace Route to a host.
tr: Delete characters, translate or squeeze them.
tsort: This is used for topological sorting.
tty: This is used for printing the filename of terminal on stdin.

U

ulimit: This commands limits the user resources.
umask: This is used to determine the file permission for a new file.
umount: This command will unmount a device from the system.
unalias: This command will remove an alias.
uname: This command will print the system information.
unexpand: This command will convert the spaces in a file to tabs.
uniq: This command will uniquify your files.
units: This will convert the units from one scale to another.
unset: This command removes the variable names or the function names.
unshar: This command unpacks the shell archive scripts.
until: This command will execute a command until there is an error.
uptime: This command will show the uptime.
useradd: Use this command when you need a new user account to be created.
userdel: This command will delete an user account from your system.
usermod: Self explanatory, modify an user account.
users: This command gives you a list of users who are currently logged in.
uuencode: This command will encode binary files.

V

v: This command lists the contents of a directory.
vdir: Same as above.
vi: This is a text editor.
vmstat: This command will report on the virtual memory statistics.

W

wait: This command directs the system to wait for a process to finish.
watch: This command will display or execute a program periodically.
wc: This command prints the word, byte and line counts.
whereis: This command will search a user’s $path, source files and man pages 
which: This command searches only for a user’s $path for a program.
while: Use this to execute commands.
who: This command will print the usernames that are currently logged into the system.
whoami: This is a command that prints the current name and user id.
wget: This will retrieve the web pages or files through HTTP, HTTPS or FTP.
write: Use this to send messages to other users.

X

xargs: This command execute’s a utility and passes a constructed argument list.
xdg-open: This lets you open an URL or a file in the user's preferred application.

Y
yes: This command will print a string until it is interrupted. 
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