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Command used in Linux. part -4

# systemctl --- For managing services on a RHEL 7 system

# service --- Run a system V init script

# tar ---- To compress files and folders

# touch --- To create or update a file.

# type --- to know any specific command is shell builtin or not

# !! --- To repeats the last command

# uptime –V --- It shows the version

# uname --- Print system information

# users --- Show the user name

# uptime --- Display the current uptime

# umount --- To unmounts the drive

# vgcreate --- To create volume group

# whatis --- Describe briefly of any command

# which --- determine the position of any command

# whoami --- To know the user name


Command used in Linux. part -3

# man --- man stands for manual. It is the command reference book of linux


# makewhatis --- to update database 

# mkdir --- To create directory

# more --- It allows quickly view file and shows details in percentage

# mount --- To mount a drive

# partprobe --- command is used to inform the operating system of partition table 
changes.

# passwd --- To set or modify password of the user

# pvcreate --- To create physical volume

# ps --- To find process ID

# pwd --- To know the present working directory

# parted — A disk partition manipulation program


# pr –x --- Divides the file into x columns

# pr –h --- Assigns a header to the file


# pr –n --- Denote the file with the number

# poweroff = init 0

# rm --- To remove file or directory without prompting for confirmation

# rm –rf --- To remove file or directory if it has content

# rm –r --- Delete directory


# rm –I file1 file2 --- prompt to the user to delete every file

# reboot = init 6

# reset --- Reset the terminal

# runlevel --- Print previous and current Sysv run level

# rm –f --- Forcely remove file

# rmdir --- To remove the emptey directory

# su --- To switcher user

# sudo --- Allow regular user to run program with the security privileges of super user 
or root.

# shutdown –h now --- Shutdown the system now and do not reboot.

# service --- It call script located /etc/init.d directory

# ssh --- To login into remote host securely

# sftp --- To connect remote ftp host




Command used in Linux. part -2

# ip addr show --- To show IP  address

# ip addr add --- To add IP address

# ip addr del --- To delete IP address

# sudo --- Offers another approach to giving users administrative access.

# ip link set dev eth1 up --- To make the state of device eth1 up

# ip link set dev eth1 down --- To make the state of device eth1 down

# ip route show ---- To check the routing table information

# ip route del --- To removed assigned static routing

# kill --- To terminate process

# last --- Can watch user’s activity in the system

# lvcreate --- To create logical volume

# ls –l test --- To show the permission of only test file.

# ls –l /tmp --- List files under directory /tmp

# ls --- To show file or directory under the current directory.

# ls –R --- To show subdirectories  and all.

# ls –a --- To show hidden file

# ls –r --- Show files and directories in reverse order

# ls –ltr --- Show latest modification file or directory date as last

# ls –version --- Show the version of ls command

# ls –l --- To show the file and directory under the current directory in details ones.

# less --- It allows quickly view file

Command used in Linux. part -1

# adduser or useradd --- To add new user

# cd.. --- To go back one state

# cd / --- To go under the root

# cd --- To change directory

# cd ~ --- To go home directory

# cd ~ <user_name> --- go to user home directory

# cd - ___ go to previous working directory

# cp --- Copy a file from one location to another

# cal --- Show the calendar of the month

# cat --- To show a specific file on the screen.

# chkconfig --- Updates and queries run level information for system services

# clear --- To delete all the previous content of the shell. Same command is CTRL –l

# crontab –l --- List schedule jobs for current user

# crontab -e --- create a new crontab

# crontab -r --- Remove a cron table and cancel all schedule jobs

# cp -p --- To copy file from source to destination preserving same mood

# cp –i --- To be prompted before overwrite it

# date --- To show the current date and time

# df –h --- To show the partition status

# df –hT --- To show the partition status details

# echo --- Display text on the screen. Mostly used when writing shell command.

# exit --- Logout from the current session.

# free --- To shows free, total and swap memory information in bytes

# free –t --- To shows total memory used and available to use in bytes

# find --- To search files, strings and directories

# ftp --- To connect remote ftp host

# fdisk --- To know the partition of the current directory

# fdisk –l --- To show the details of partition of the current directory

# groups --- Show groups you are in

# grep <search_string> ---- Can find a specific string by this command

# grep –w ---- Shows all the lines that do not matched the searched string

# grep –c ---- Display only the count of matching lines

# grep –m --- Show the matching line and its number

# grep –i --- Match both (upper and lower case)

# grep –l --- Shows just the name of the file with the string

# head --- Display the first few lines of the text file.

# history --- To show all previous command



What does it mean in Linux ? Part - 1


In Linux the syntax has special meaning. Some of them are given bellow:

# cat <file1> <file2> > <new file> --- To combine file1 and file2 into new file.

# cat <file> --- It show the content of the file . Cat command can be displayed only the text file.

# chown guru99 : guru99 test --- change user as guru99 and group as guru99 of test file at a time.

# rm <file> --- Delete file

# cat > <file> ---- Write content into this file. Then press Ctrl + D to come back to shell.

# chgrp root test --- Change groups as root of test file.

# chmod g+x test --- Add execute permission to the group for the test file.

# cp <source_file> <destination_file> --- Copy source file to destination file


# ls <ABC> <DEF> --- List the content of both directories <ABC> <DEF>

# ls ABC DEF > dirlist --- Standard output redirection to the dirlist


# cat sample | grep a --- Look for line containing the character a

# cat sample | grep ^a --- Look for the line which start with a.

# cat sample | grep t$ --- Look for the line which end with character.

# cat sample | grep –E p\{2} --- Look for the line where character  p appearing exactly two times one after the other. [as for example: apple]

# cat sample | grep “a\+ t” --- Look line where character a precede character t.

# ls ABC DEF > dirlist 2>&1 --- It will redirect error output to the standard output and standard output to the dirlist.


# echo {aaa, bbb, ccc, ddd} --- aaa bbb ccc ddd

# echo {a . . z} --- a b c d e f g h I j k l m n o p q r s t u v w x y z

# echo {1 . . 11} --- 1 2 3 4 5 6 7 8 9 10 11

# echo a{0 . . 9}b --- a0b a1b a2b a3b a4b a5b a6b a7b a8b a9b a10b


# lp –nc <filename>  --- Prints c copies of file

# lpr c <filename> --- Prints c copies of file

# lp –d <printer_name> <file_name> --- specify name of the printer

# lp –p <printer_name> <file_name> --- Specify name of the printer

# ps <PID_number> --- To know the status of the specific process


# pidof <process_name> --- To know the pid of the specific process

# mailx <address> <body> --- Command to send mail

# mv <source_file> <destination_file> --- Move (cut) source file to destination file 

# Chmod o=rwx test --- Set permission for other on tset file

# chmod u-r test --- Remove read permission to the user for the test file.

# mkdir /temp/music --- Create music directory under temp directory.

# rmdir <directory name> --- Remove directory and sub-directory of the directory.

# mkdir <dir1> <dir2> <dir3> --- Create multiple directory at a time.

# chmod <permission> <filename> --- This mean Change Mode. This command is used is set permission (read, write and execute) on a file/directory for the owner, group and the world. [Exmp. Chmod 764 test]

# mv <directoryname> <newdirectoryname> --- Move a file to a new location or rename it. Need to be superuser.

Abbreviation related with Linux

Some term related with Linux

ACL --- Access Control List

ANTP --- All Numeric TCP Protocol

BIOS --- Basic Input output System

BIND --- Berkeley Internet Domain Name

CIFS --- Common Internet File System

Crond --- Cron Demon

CUPS --- Common Unix Printing System

DAT --- Digital Audio Tape

DDS --- Digital Data Storage

DHCP --- Dynamic Host Configuration Protocol

DNAT --- Destination NAT

FHS --- Filesystem Hierarchy Standard 

FQDN --- Fully Qualified Domain Name

GNU --- GNU is not Linux

GPL --- General Public Licence

GRUB --- Grand Unified Boot loader

IANA ---- Internet Assigned Numbers Authority

ICANN --- Internet Corporation for Assigned Names and Numbers

IETF --- Internet Engineering Task Force 

IRR --- Internet Resources Register-er

ITP --- Internet Rime Protocol

KVM --- Kernel-base Virtualization Module

LDAP --- Lightway Directory Access Protocol

LDIF --- LDAP Data Interchange File

LPD --- Line Print Daemon

LUKS --- Linux Unified Key Setup

LV --- Logical Volume

LVM --- Logical Volume Management

MAC --- Mandatory Access Control

MBR --- Master Boot Recoder

MDA --- Mail Delivery Agent

MTA --- Mail Transfer Agent

MUA --- Mail User Agent

NAT --- Network Address Translation

NetStat --- Network Statistic

NFS --- Network File Systems

NSA --- National Security Agency

NSS --- Name Service Switch

NTP --- Network Time Protocol

PAM --- Pluggable Authentication Modules

PID --- Process Identification

POST --- Power On Self Test

PV --- Physical Volume

PXE --- Pre-boot Execution Environment

RADIUS --- Remote Authentication Dial In User Service

RAID --- Redundant Array of Independent Disk

RHEL --- Redhat Enterprise Linux

RPM --- Redhat Package Manager

SAN --- Storage Area Network

SCSI --- Small Computer System Interface

SELinux --- Security Enhanced Linux

SMB --- System Message Block

SNAT --- Source NAT

SWAT -- Samba Web Administration Tools

SSH --- Secure Shell

TFTP --- Trivial File Transfer Protocol

UUCP --- Unix to Unix Copy

VG --- Volume Group

VNC --- Virtual Network Computing

YUM --- Yellow-dog Update Modifier