Basic Commands Part1

 

Command	Option	Description
1. Uname	uname -r uname -n	To find the version of unix os To find the machine name
2. Man	man grep man -e grep man -k copy	Print the user manual for any command. To find the user manual for grep command. One line definition of grep usage. Helpful when we donot know which command will solve the purpose.e.g :- gives the different option available for copying.
3.Cal	cal 2009 cal dec	Print the calendar year or month Print the calendar 2009 year Print calender for current december month
4. Date	date date +%m date +%h date +'%h%m' date +%d date +%y H,M and S	Tue Mar 09 07:10:10 IST 2009 3 March Mar-03 10 9
5.Who	who who am I who -H who -u	Login details of all the users in system Login details for only myself Login details for all users with headers info Login details for only active users
6.Passwd		To change the password
7.Lock	lock -45	lock the terminal for 45 minutes
8.Bc		To use the calculator
9.ls	ls -x ls -F ls -a ls -r ls -x abc ls -R ls -ld ls -il testfile ls -lt ls -ltr ls -lut	To Print the contents of current directory. Prints Multi column output of files with their names. To Print only directoris and executable files.< * > indicate all files containing executable code and </> indicate the directories. Print all files including hidden files. <a> stands for all. Reverse the sort order of all the files with their names. Print the content of abc directory. Print all files and sub-directories in directory TREE. Print all the directories. Prints the inode number of file. Prints all the file with their last modification time keeping latest modified at top. Prints all the file with their last modification time in reverse order keeping last modified at bottom. prints last access time of files.
10.Cat	cat testfile cat > testfile	Print the content of any file. Create a new file with testfile name.
11.CP	cp -i testfile abc cp -r abc newabc	To copy file and directories. copying testfile to abc directory interactively. copying entire directiry structure abc to newabc recursively.
12.rm	rm -f newabc rm -r newabc	All the options of cp command is applicable for rm command. Removing directory newabc forcefuly. Recursive deletion will not remove the write protected files.
13.lp		Used for Printing the files
14.Split	split testfile split -72 testfile split testfile newfile	To split the big files in different small files of 1000 lines each<default>. Split the files into small files. change the default split line size to 72. Renaming the testfile to new name as <newfile>.
15. Cmp     comm     Diff		These three command are used to find the difference in two files
16.wc	wc -w testfile wc -c testfile wc -l testfile wc testfile	Print the numbers of words, lines and character in the file
17.Path	PATH=$PATH:/home/ gagan:/home/deep	Set the path variable for SHELL to use these directory path to locate the executables commands.
18.stty	stty -a   stty intr \^c stty eof \^a	Print current setting of terminal To delete the character during backspacing To change the interrupt key to Ctrl c instead of 'DELETE' default To change the termination control of input during file creation using cat command from Ctrl d to Ctrl a.
19.Alias	alias alias l ='ls -ltr' alias showdir ='cd $1;ls -l' unalias	Print all the alias set in the system. To create short hand names of command. Passing positional parameter ETL to showdir alias will take us to that directory. To redefine and unset the alias.
20.History	history -5 history 10 15 HISTSIZE 1200	To find the previous command that has been used. Print the last 5 command that has been used. Every command has event number. Display event number between 10 an d15. To change the defalult setting of command history saving feature.
21. r       !!	r-2 r 20	Repeat previous command in Korn Repeat previous command in Bash Repeat previuos to prevoius command Repeat the command with 20 event number.
22.Tilde(~)		Changes control to home directory Changes absolute path home directory of user a_cmdb, the value of home directory can be seen by $HOME environment variable
23.cd -		To switch between current working directory and most recently used directory.
24.chmod	chmod u+rwx newfile chmod g+x newfile chmod 757 newfile chmod 457 newfile chmod -R a+x abc chmod -R 001 .	Changing the permission of file for user <u>, group <g>, others <o> or all <a> with + as assign , - as remove and = as absolute permission.r read<4>, w write<2> and x execute<1>.         Recursively changes the permission to execute for all directory and sub directory in abc directory for all users. . Indicate the current directory.