basic unix commands for dba

8/12/2019 Basic Unix Commands for DBA

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Basic Unix commands for DBA

Command Syntax Description

1 man man command

man ls

Display the manual of the command, this will listall the options which can used by the command.

To exit out of the manual you need to press q.

2. ls ls

ls -a

ls -ltr

List all the files under your current directory.

List all the hidden files.

List files with date, sorted in the date modified,

oldest first.

-rw-r--r-- 1 oracle oinstall 0 Oct 13 20:21 test.txt.

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

3. clear clear To clear the screen

4. pwd pwd Displays the Present/Current Working Directory

.

5. cd cd [directory name]

cd Test

cd ..

cd ~

Change directory, without argument will change

your working directory to your home directory.

Change working directory to "Test".Change working directory to one directory

backwards (.. is parent and . is current

directory).

~ is also referred as home directory.

description of the

output from ls -ltr


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6. touch touch filename

touch test.txt

Create a 0 byte file or to change the timestamp

of file to current time .

This will create a file called as test.txt.

7. mkdir mkdir directory name

mkdir test_1

mkdir -p

mkdir directory1 directory2

To Create a Directory .

This will create a directory called as test_1,in the

current path.

Create directory down many levels in single

command.

mkdir -p

/home/oracle/test_1/test_2/test_3/test_4

This will create multiples directories in one

command, in the current path

8. rmdir rmdir directory name

rmdir test1

To remove a empty directory.

This will remove a empty directory named astest1.

9. rm rm filename

rm -rf directory name

To remove a file( with data or without data).

Remove directory with files. Note- 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.

When you -i flag it ask for confirmation before

deleting it.

9. cp cp filename newfilename

cp -r* newpath

Copy a file.

To copy all files and subdirectories to a new

location, use -r flag to recursively copy.

10. mv mv filename newfilename

mv filename directoryname

mv filename

directoryname/newfilename

mv * directotyname

Rename (Move) a file. Rename filename to new

filename.

Move filename under directory name with the

same file name.

Move filename to directory name as new

filename.

If you use a wildcard * in the filename, It will

move all the files to directory name specified in

the command.

11. file file filename To see what kind of file, whether editable.

Executable files are binary and you should not

open them.


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12. cat cat filename

cat filename1 filename2

filename3 > new_filename

See contents of a text file. cat (catenae) will list

the whole file contents. Cat is mostly used to

catenae two or more files to one file using the

redirection operator.

Catenae the contents of filename1, filename2

and filename3 to a single file called

new_filename. If you do not use the

redirection(>), then the result will be shown on

the standard output, i.e., screen.

13. 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.

14 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

15. tail tail -n filename

tail -10 filename

tail -f filename

To see the specified number of lines from theend of the file. where m is number of lines.

will display last 10 lines from filename.

will display the current appending output in the

filename.

16. head head -n filename To see the specified number of lines from the

top of the file.

17. env env

To set an environment

variable:

echo $VARIABLENAME

To see value of all environment variables.

In ksh or sh

"export VARIABLENAME=value", Note there is

no space between =.

See value of an environment variable


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18. echo echo string

echo "Oracle SID is

$ORACLE_SID"

To print the string to standard output.

Will display "Oracle SID is ORCL" if the value of

ORACLE_SID is ORCL.

19. chmod chmod permission filename

chmod +rwx filename

chmod 777 filename

chmod u+rwx,g+rx,o-rwx

filename

chmod 750 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 = 4r_x = 101 = 5

Give all permissions to everyone on filename

Read, write, execute for owner, read and

execute for group and no permission for others

20. chown chown newuser filename Change owner of a file

21. chgrp chgrp newgroup filename

chown newuser:newgroup

filename

Change group of a file

Change owner and group of file.

22. compress compress filename Compress a file - compressed files have

extension .Z. To compress file you need to have

enough space to hold the temporary file.

23. uncompress uncompress filename Uncompress a file


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24. df df [options] [mountpoint]

df -k /u01

df -k .

Free space available on the system (Disk Free);

without arguments will list all the mount points.

Free space available on /u01 in Kilobytes.

If you're not sure of the mount point name, go

to the directory where you want to see the free

space and issue this command, where "."

indicates current directory. You can use df -h to

display the sizes in GB.

25. du du [-s] [directoryname]

du -s

Disk used; gives operating system blocks used by

each subdirectory. To convert to KB, for 512K OS

blocks, divide the number by 2.

gives the summary, no listing for subdirectories

26. find Find files.

find /home/oracle -name

"*.txt" -print

find . -name "*log" -print

-exec rm {} \;

find is a very useful command, searches

recursively through the directory tree looking for

files that match a logical expression(search

string). It has many options and is very powerful.

Simple use of find - to list all files whose name

ending with .txt under /home/oracle and its

subdirectories.

to delete files whose name end in log. If you do

not use the "-print" flag, the file names will notbe listed on the screen.


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27. grep Global regular expression

print

grep oracle /etc/passwd

grep -i -l EMP_TAB *.sql

grep -v '^#' /etc/oratab

to search for an expression in a file or group of

files. This is a very useful command, especially to

use in scripts.

to display the lines containing "oracle" from

/etc/passwd file.

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 extension.

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).

28. mail mail "[email protected]"

basic unix commands for dba

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