Basic Unix Commands

 

Basic Unix commanads in One page !!  

Command	Meaning
ls	list files and directories
ls -a	list all files and directories
mkdir	make a directory
cd directory	change to named directory
cd	change to home-directory
cd ~	change to home-directory
cd ..	change to parent directory
pwd	display the path of the current directory
cp file1 file2	copy file1 and call it file2
mv file1 file2	move or rename file1 to file2
rm file	remove a file
rmdir directory	remove a directory
cat file	display a file
less file	display a file a page at a time
head file	display the first few lines of a file
tail file	display the last few lines of a file
grep ‘keyword’ file	search a file for keywords
wc file	count number of lines/words/characters in file
command > file	redirect standard output to a file
command >> file	append standard output to a file
command < file	redirect standard input from a file
command1 | command2	pipe the output of command1 to the input of command2
cat file1 file2 > file0	concatenate file1 and file2 to file0
sort	sort data
who	list users currently logged in
*	match any number of characters
?	match one character
man command	read the online manual page for a command
whatis command	brief description of a command
apropos keyword	match commands with keyword in their man pages
ls -lag	list access rights for all files
chmod [options] file	change access rights for named file
command &	run command in background
^C	kill the job running in the foreground
^Z	suspend the job running in the foreground
bg	background the suspended job
jobs	list current jobs
fg %1	foreground job number 1
kill %1	kill job number 1
ps	list current processes
kill 26152	kill process number 26152

UNIX- Environment Variable

1.How to set\unset an environment variable in unix

ENVIRONMENT variables are set using the setenv command, displayed using the printenv or env commands, and unset using the unsetenv command.

To show all values of these variables, type

% printenv | less

2.what is the difference between PATH and path in UNIX

In general, environment and shell variables that have the same name (apart from the case) are distinct and independent in Unix.

PATH represents an environment variable  where as path represents a shell variable.

 

Q & A : Linux packaging

Packaging software with RPM

The Red Hat Package Management system is a well-designed, fully functional, user-friendly method of managing applications and programs within the Linux environment. The RPM technology was unique to Red Hat Linux, but it is also using with many other distributions, such as Mandrake, Caldera, and SuSE.

 What is a Package Management System?

Package Management System is a collection of tools to automate the process of installing ,upgrading,configuring and removing applications,which also comprises tracking for version updates and dependencies.

 Eg: RPM,dpkg,emerge,urpmi

 What is RPM?

 RedHat Package Manager (RPM) is one of the package Management System (PMS) ,primarily intended for Linux distributions.

 RPM allows to take the source code for newsoftwsre and package it into source and binary form,such that binaries can be easily installed and tracked and source can be rebuilt.