Common Unix Commands

These are few of the common UNIX commands Oracle DBAs would use. I have provided brief explanation of commands and examples. In UNIX, most commands have a lot of options available. For a complete list of options, see the UNIX online manual pages. All UNIX commands and file names are case sensitive. This page is to let you know the commands in UNIX, which might give you a start to learn more about the command using the manual pages or from UNIX books

man	man command	Manual Pages - Help with any UNIX command
	man ps	Help on the UNIX ps command
clear	clear	To clear the screen
pwd	pwd	Present / Current Working Directory
cd	cd [directoryname]	Change directory, without argument will change your working directory to your home directory.
	cd work	Change working directory to "work"
	cd ..	Change working directory to parent directory (.. is parent and . is current directory)
ls	ls [-options] [names]	List files. [names] if omitted, will list all files and subdirectories in the directory. Wild cards can be specified.
	ls -l	List files with date and permissions -rw-rw-r-- 1 oracle dba 706 Sep 23 17:26 storparms.sql -rwxrwx--- 1 oracle dba 377 Aug 28 15:00 sysdelstat.sql drwxrwxr-- 2 oracle dba 2048 Oct 22 16:12 work [column1] [2] [3] [4] [5] [6] [7] Column1 - Permissions of the file or directory; r-read, w-write, x-execute Position 1 indicates if it is a directory Positions 2-4 is the permission for owner Positions 5-7 is the permission for group Positions 8-10 is the permission for others Column2 - Owner of the file/directory Column3 - Group which the owner belogs to Column4 - Size of the file in bytes Column5 - Last Modified Date Column6 - Last Modified Time Column7 - Name of the file/directory
	ls -al	List files with date and permissions including hidden files
	ls -lt	List files with date, sorted in the date modified
	ls -ltr bt*	List files with date, sorted in the date modified, oldest first, with filenames starting with bt
Wildcards	*	Any character, any number of positions
	?	Any character, one position
	[]	A set of characters which match a single character position.
	-	To specify a range within []
	ls *x*	List all files which contains an x in any position of the name.
	ls x*	List all files which start with x
	ls *T0[1-3]ZZ	List all files which contain T0 followed by 1,2 or 3 followed by ZZ. The following files match this condition: analyzeall.AAAT01ZZ dbaoc_err.AAAT03ZZ dbstart_log.AAAT03ZZ calerterr.AAAT01ZZ dbaoc_log.AAAT01ZZ
	ls job?.sql	List files which start with job followed by any single character followed by .sqlExample: jobd.sql jobr.sql
	ls alert*.???[0-1,9]	alert_AAAT01ZZ.1019 alert_AAAD00ZZ.1020 alert_AAAI09ZZ.1021
touch -	touch filename	Create a 0 byte file or to change the timestamp of file to current time (wild cards as above can be used with the file names)
mkdir	mkdir directoryname	Create Directory
	mkdir -p directorypath	Create directory down many levels in single passmkdir -p /home/biju/work/yday/tday
rmdir	rmdir directoryname	Remove directory
rm	rm filename	Remove file
	rm -rf directoryname	Remove directory with files. Important - There is no way to undelete a file or directory in UNIX. So be careful in deleting files and directories. It is always good to have rm -i filename for deletes
cp	cp filename newfilename	Copy a file
	cp -r * newloc	To copy all files and subdirectories to a new location, use -r, the recursive flag.
mv	mv filename newfilename	Rename (Move) a file. Rename filename to newfilename.
	mv filename directoryname	Move filename under directoryname with the same file name.
	mv filename directoryname/newfilename	Move filename to directoryname as newfilename.
	mv * destination	If you use a wildcard in the filename, mv catenates all files to one sigle file, unless the destination is a directory.
	cp -i file1 file2 mv -i file1 file2 rm -i file*	Use the -i flag with rm, mv and cp to confirm before destroying a file.
file	file filename	To see what kind of file, whether editable. Executable files are binary and you should not open them.
	file d*	dbshut: ascii text dbsnmp: PA-RISC1.1 shared executable dynamically linked -not stripped dbstart: ascii text dbv: PA-RISC1.1 shared executable dynamically linked -not stripped demobld: commands text demodrop: commands text
vi	vi filename	Edit a text file. Vi is a very powerful and "difficult to understand" editor. But once you start using, you'll love it! All you want to know about vi are here. More vi tricks later!!
cat	cat filename	See contents of a text file. cat (catenate) will list the whole file contents. Cat is mostly used to catenate two or more files to one file using the redirection operator.
	cat file1 file2 file3 > files	Catenate the contents of file1, file2 and file3 to a single file called files. If you do not use the redirection, the result will be shown on the standard output, i.e., screen.
more page	more filename page filename	Show the contents of the file, one page at a time. In more/page, use space to see next page and ENTER to see next line. If you wish to edit the file (using vi), press v; to quit press q.
tail	tail -n filename	To see the specified number of lines from the end of the file.
head	head -n filename	To see the specified number of lines from the top of the file.
pg	pg filename	To show the contents of the file, page by page. In pg, you go up and down the pages with + and - and numbers.
		1 First Page of the file $ Last Page of the file +5 Skip 5 pages -6 Go back 6 pages ENTER Next page - Previous Page q Quit /string Search for string
env	env	To see value of all environment variables.
	To set an environment variable:	In ksh or sh "export VARIABLENAME=value", Note there is no space between =. In csh "setenv VARIABLENAME value"
	echo $VARIABLENAME	See value of an environment variable
echo	echo string	To print the string to standard output
	echo "Oracle SID is $ORACLE_SID"	Will display "Oracle SID is ORCL" if the value of ORACLE_SID is ORCL.
lp	lp filename	To print a file to system default printer.
chmod	chmod permission filename	Change the permissions on a file - As explained under ls -l, the permissions are read, write, execute for owner, group and others.
		You can change permissions by using numbers or the characters r,w,x. Basically, you arrive at numbers using the binary format.Examples: rwx = 111 = 7 rw_ = 110 = 6 r__ = 100 = 4 r_x = 101 = 5
	chmod +rwx filenamechmod 777 filename	Give all permissions to everyone on filename
	chmod u+rwx,g+rx,o-rwx filenamechmod 750 filename	Read, write, execute for owner, read and execute for group and no permission for others
chown	chown newuser filename	Change owner of a file
chgrp	chgrp newgroup filename	Change group of a file
	chown newuser:newgroup filename	Change owner and group of file
compress	compress filename	Compress a file - compressed files have extention .Z. To compress file you need to have enough space to hold the temporary file.
uncompress	uncompress filename	Uncompress a file
df	df [options] [moutpoint]	Freespace available on the system (Disk Free); without arguments will list all the mount points.
	df -k /ora0	Freespace available on /ora0 in Kilobytes. On HP-UX, you can use "bdf /ora0".
	df -k .	If you're not sure of the mount point name, go to the directory where you want to see the freespace and issue this command, where "." indicates current directory.
du	du [-s] [directoryname]	Disk used; gives operating system blocks used by each subdirectory. To convert to KB, for 512K OS blocks, divide the number by 2.
	du -s	gives the summary, no listing for subdirectories
find	Find files.	find is a very useful command, searches recursively through the directory tree looking for files that match a logical expression. It has may options and is very powerful.
	find /ora0/admin -name "*log" -print	Simple use of find - to list all files whose name end in log under /ora0/admin and its subdirectories
	find . -name "*log" -print -exec rm {} \;	to delete files whose name end in log. If you do not use the "-print" flag, the file names will not be listed on the screen.
grep	Global regular expression print	to search for an expression in a file or group of files. grep has two flavours egrep (extented - expands wild card characters in the expression) and frep (fixed-string - does not expand wild card characters). This is a very useful command, especially to use in scripts.
	grep oracle /etc/passwd	to display the lines containing "oracle" from /etc/passwd file.
	grep -i -l EMP_TAB *.sql	to display only the file names (-l option) which contains the string EMP_TAB, ignore case for the string (-i option), in all files with sql extention.
	grep -v '^#' /etc/oratab	display only the lines in /etc/oratab where the lines do not (-v option; negation) start with # character (^ is a special character indicating beginning of line, similarly $ is end of line).
ftp	ftp [hostname]	File Transfer Protocol - to copy file from one computer to another
	ftp AAAd01hp	invoke ftp, connect to server AAAd01hp.
	Connected to AAAd01hp.com. 220 AAAd01hp.com FTP server (Version 1.1.214.2 Mon May 11 12:21:14 GMT 1998) ready. Name (AAAd01hp:oracle):BIJU	program prompts for user name, enter the login name to AAAd01hp.
	331 Password required for BIJU. Password:	enter password - will not be echoed.
	230 User BIJU logged in. Remote system type is UNIX. Using binary mode to transfer files. ftp> ascii	Specifying to use ASCII mode to transfer files. This is used to transfer text files.
	200 Type set to A. ftp> binary	Specifying to use binary mode to transfer files. This is used for program and your export dump files.
	200 Type set to I. ftp> ls	To see the files in the remote computer.
	200 PORT command successful. 150 Opening ASCII mode data connection for /usr/bin/ls. total 8 -rw-rw-rw- 1 b2t dba 43 Sep 22 16:01 afiedt.buf drwxrwxrwx 2 b2t dba 96 Jul 9 08:47 app drwxrwxrwx 2 b2t dba 96 Jul 9 08:49 bin -rw-rw-rw- 1 b2t dba 187 Jul 30 14:44 check.sql 226 Transfer complete. ftp> get check.sql	transfer the file check.sql from the remote computer to the local computer. The file will be copied to the present directory with the same name. You can optionally specify a new name and directory location.
	200 PORT command successful. 150 Opening BINARY mode data connection for check.sql (187 bytes). 226 Transfer complete. 187 bytes received in 0.02 seconds (7.79 Kbytes/s) ftp> !ls	! runs commands on the local machine.
	AAAP02SN a4m08.txt tom3.txt a4m01.txt ftp> put a4m01.txt/tmp/test.txt	transfer file from local machine to remote machine, under /tmp directory with name test.txt.
mail	mail "xyz@abc.com" < message.log	Mail a file to internet/intranet address. mail the contents of message.log file to xyz@abc.com
	mail -s "Messages from Me" "xyz@abc.com" "abc@xyz.com" < message.log	mail the contents of message.log to xyz and abc with a subject.
who	who [options]	to see who is logged in to the computer.
	who -T	Shows the IP address of each connection
	who -r	Shows when the computer was last rebooted, run-level.
ps	ps	process status - to list the process id, parent process, status etc. ps without any arguments will list current sessions processes.
	ps -f	ull listing of my processes, with time, terminal id, parent id, etc.
	ps -ef	as above for all the processes on the server.
kill	kill [-flag] processid	to kill a process - process id is obtained from the ps command or using the v$process table in oracle.
	kill 12345	Kill the process with id 12345
	kill -9 12345	To force termination of process id 12345
script	script logfilename	to record all your commands and output to a file. Mostly useful if you want to log what you did, and sent to customer support for them to debug. start logging to the logfilename. The logging is stopped when you do "exit".
hostname	hostname	displays the name of the computer.
uname	uname -a	to see the name of the computer along with Operating system version and license info.
date	date	displays the current date and time.
	date "+%m%d%Y"	displays date in MM/DD/YYYY format
cal	cal	displays calender of current month
	cal 01 1991	Displays January 1991 Calender
telnet	telnet [hostname]	to open a connection to another computer in the network. Provide the alias name or IP address of the computer.
&	command &	add & to the end of the command to run in background
	nohup command &	no hangup - do not terminate the background job even if the shell terminates.
fg	fg	to bring a background job to foreground
bg	bg	to take a job to the background. Before issuing this command, press ^Z, to suspend the process and then use bg, to put it in the background.
jobs	jobs	to list the current jobs in the shell.
rcp	rcp [-r] sourcehost:filename destinationhost:filename	Remote copy. Copy files from one coputer to another. To set up the computer for remote copy and remote login (rlogin) will be discussed later.
	rcp host1:/ora0/file1.txt host2:/ora0/temp/file1.txt	Copy file from host1 to host2. If the computer name is omitted, the hostname is assumed.

Part 2 - Using UNIX Commands

To see errors from Alert log file

cd alertlogdirectory;
grep ORA- alertSID.log

To see the name of a user from his unix id (Provided your UNIX admin keeps them!)

grep userid /etc/passwd

To see if port number 1521 is reserved for Oracle

grep 1521 /etc/services

To see the latest 20 lines in the Alert log file:

tail -20 alertSID.log

To see the first 20 lines in the Alert log file:

head -20 alertSID.log

To find a file named "whereare.you" under all sub-directories of /usr/oracle

find /usr/oracle -name whereare.you -print

To remove all the files under /usr/oracle which end with .tmp

find /usr/oracle -name "*.tmp" -print -exec rm -f {} \;

To list all files under /usr/oracle which are older than a week.

find /usr/oracle -mtime +7 -print

To list all files under /usr/oracle which are modified within a week.

find /usr/oracle -mtime -7 -print

To compress all files which end with .dmp and are more than 1 MB.

find /usr/oracle -size +1048576c -name "*.dmp" -print -exec compress {} \;

To see the shared memory segment sizes

ipcs -mb

To see the space used and available on /oracle mount point

df -k /oracle

To see the users logged in to the server and their IP address

who -T

To change passwd of oracle user

passwd oracle

To convert the contents of a text file to UPPERCASE

tr "[a-z]" "[A-Z]" < filename > newfilename

To convert the contents of a text file to lowercase.

tr "[A-Z]" "[a-z]" < filename > newfilename

To kill a process from Unix.

kill unixid OR
kill -9 unixid

To see the oracle processes

ps -ef | grep SIDNAME

To see the number of lines in a text file (can be used to find the number of records while loading data from text file).

wc -l filename

To change all occurrences of SCOTT with TIGER in a file

sed 's/SCOTT/TIGER/g' filename > newfilename

To see lines 100 to 120 of a file

head -120 filename | tail -20

To truncate a file (for example listener.log file)

echo '' > filename