- ls
- pwd
- ln
- head
- tail
- cal
- ps
- kill
- who
- whoami
- uptime
- ut
ls : This command displays files and directories in columnar format.
Example:
$ ls
$ ls -S
Arrange the files based on the size(S is upper letter)
Arrange the files based on the size(S is upper letter)
$ ls -l
long listing the files
long listing the files
$ ls -a
Displays hidden files
Displays hidden files
$ ls -i
Displays inodes for each file
Displays inodes for each file
$ ls -R
Displays all directories along with subdirectories in current working directory.
Displays all directories along with subdirectories in current working directory.
Creating a hidden file:
$ cat >.employee.txt
Wild card characters using with ls command.
? Represents single character
* Represents group of characters
[ ] Represents searching pattern
Examples:
$ ls ? Displays files with one letter
$ ls x* Displays files which are starting with 'x'
$ ls ??? Displays files with 3 letters
$ ls *.out Displays all the files with extension 'out'
$ ls [a-z] Displays single character files which are from a to z
$ ls [a-z]* Displays files starting with a to z
$ rm ? Removes the files with single character
$ rm *.c Removes the files with extension 'c'
$ cp ? chennai Single digit files will be copied into directory 'chennai'
pwd : This command shows current working directory in unix
$ pwd
head : Used to display First lines of the file
Syntax:
$ head -n filename
Example:
$ head paypal.txt
This command dispalys default 10 lines of the file paypal.txt
$ head -n15 paypal.txt
This command displays 15 lines of the file paypal.txt
$ head -n3 paypal.txt
This command displays 3 lines of the file paypal.txt
tail : Used to display last lines of the file.
Ex:
$ tail paypal.txt
This command displays default last 9 lines.
$ tail -n5 paypal.txt
This command displays last 4 lines of the file.
$ tail -n15 paypal.txt
This command displays last 14 lines of the file.
cal: Used for display the calendar.
Syntax:
$ cal
$ cal [Month No] [Year]
Ex:
$ cal 2011 Displays 2011 calendar
$ cal 2 2011 Displays Feb month in 2011 year
ln :
1.This will create link between 2 files.(2nd file should new one)
2. If one file modified another one affected.
Ex:
$ln paypal.txt funpal.txt
ps : Knowing background process running /stopped
$ ps pid
kill : Used for terminating the process
Ex:
$ kill pid
who : Used for to display who are working in the system
Ex:
$ who
whoami: Display my user name/account
Ex:
$ whoami
uptime: This command used for display load in the server.
$ uptime
ut: displays current unix time
advance_date : Used to time forward the unix server.
$ advance_datereset_time.py : Used to reset time and date in unix server.
$ reset_time.py
advance_date : Used to time forward the unix server.
$ advance_datereset_time.py : Used to reset time and date in unix server.
$ reset_time.py
UNIX File Access Permissions
chmod: It provides permissions over a file in 3 categories.
1) owners
2) groups
3) others
Permissions which can be granted are read, write and execute
1) read (r)
2) write (w)
3) execute (e)
These permissions are represented with numeric values
r - 4
w - 2
e - 1
-----------
7
-----------
Owners are users whose files gets referred from their respective accounts.
Groups are users whose accounts are dependent on the other accounts.
Others are users who can access the files of other users.Chmod command is used to change the permissions for a file or directory.
Syntax:
$ chmod FAP Filename
* FAP is file access permissions
Examples:
$ chmod ooo paypal.txt
No permissions to owners,groups and others
$ chmod 777 paypal.txt
All permissions to owners,groups and others
$ chmod 444 paypal.txt
Read permission to owners,groups and others (4 - read)
$ chmod 600 paypal.txt
Read(4),write(2) permissions to owners, no permissions to groups and others
$ chmod 664 paypal.txt
Read,write permissions to owners,groups and read permission to others
$ chmode 111 paypal.txt
Execute permission to owners,groups and others
Change permissions using name of the permission:
Examples:
$ chmod u-w g-w o-r paypal.txt
* write permission cancelled from owner
* write permission cancelled from groups
* read permission cancelled from others
$ chmod u+rwx g+rwx o+r paypal.txt
* read,write,execute permissions added to owners
* read,write,execute permissions added to groups
* read permission added to others
** Note: + used for giving permissions.
- is used for removing permissions.
1) owners
2) groups
3) others
Permissions which can be granted are read, write and execute
1) read (r)
2) write (w)
3) execute (e)
These permissions are represented with numeric values
r - 4
w - 2
e - 1
-----------
7
-----------
Owners are users whose files gets referred from their respective accounts.
Groups are users whose accounts are dependent on the other accounts.
Others are users who can access the files of other users.Chmod command is used to change the permissions for a file or directory.
Syntax:
$ chmod FAP Filename
* FAP is file access permissions
Examples:
$ chmod ooo paypal.txt
No permissions to owners,groups and others
$ chmod 777 paypal.txt
All permissions to owners,groups and others
$ chmod 444 paypal.txt
Read permission to owners,groups and others (4 - read)
$ chmod 600 paypal.txt
Read(4),write(2) permissions to owners, no permissions to groups and others
$ chmod 664 paypal.txt
Read,write permissions to owners,groups and read permission to others
$ chmode 111 paypal.txt
Execute permission to owners,groups and others
Change permissions using name of the permission:
Examples:
$ chmod u-w g-w o-r paypal.txt
* write permission cancelled from owner
* write permission cancelled from groups
* read permission cancelled from others
$ chmod u+rwx g+rwx o+r paypal.txt
* read,write,execute permissions added to owners
* read,write,execute permissions added to groups
* read permission added to others
** Note: + used for giving permissions.
- is used for removing permissions.
UNIX Filter Commands
· grep
· sort
· more
· cut
· wc
· uniq
grep: (Global Regular Expression Pattern)
This command is used for searching a required pattern in a file.
Syntax:
$ grep [- optopn] "search pattern" Filename [redirection symbol newfilename]
Options:
-i Ignores case sensitiveness in searching pattern
-n displays line numbers for those lines which gets matched and un matched with the pattern
-c counts number of times a searching pattern exists and does not exists
-v (verbose) Displays those lines that does not match with the pattern
Example:
$ cat > paypal.txt
welcome to unix
paypal welcomes you
unix multi user os
WELCOME to the world of unix
$ grep "welcome" paypal.txt
$ grep -i "welcome" paypal.txt
$ grep -i -n "welcome" paypal.txt
$ grep -i -c "welcome" paypal.txt
$ grep -i -v "welcome" paypal.txt
$ grep -i -v -n "welcome" paypal.txt > funpal.txt
Sort : Used to arrange numbers/text in ascending/descending order.
* by default it arranges ascending order.
Syntax:
$ sort [-option] [redirection synbol ] filename [redirection synbol] [new filename]
options:
-r Arrange data in reverse or descending order
-n Arrange data in ascending or descending order by considering whole number.
* if n is not used then numbers gets arranged in order based on 1st digit.
Ex1:
$ sort > paypal.txt
6
2
9
1
5
3
$ cat paypal.txt Ascending order
$ sort -r paypal.txt > funpal.txt Descending order
$cat funpal.txt
Ex2:
$ sort >google.txt
176
2165
8
93
-----
------ [ctrl+d]
$cat google.txt It considered first digit
$sort -n google.txt > yahoo.txt It considered whole number.more: This filter command used to display information from multiple files based n page wise.It gives an identification of end of file for first file and beginning of next file.
Syn:
$more [-option] file1,file2,file3, etc...
options:
-p clears the screen and displays next file in the list of files
*note:
Enter key retrieves next file based on %s
spacebar retrieves complete data from next file
Ex: $more - p paypal.txt funpal.txtcut: Used to cut the required text from a file. It can cut the data on the columns and fields.
Syntax:
$ cut [-option] filename [redirection symbol new filename]
-c To cut the data in columns
-f To cut the data in fields that is that data which is separated by tab.
Ex1:
$ cat>paypal.txt
Hyderabad
Secunderabad
Andhra [ctrl+d]
$ cut -c1 paypal.txt [Enter]
H
S
A
$cut -c3 paypal.txt [Enter]
d
c
d
$cut -c1 -3 paypal.txt [Enter]
Hyd
Sec
And
Ex2:
$cat > funpal.txt [Enter]
India Delhi
Andhra Hyderabad
Peers Net
[ctrl+d]
$ cut -f1 funpal.txt [Enter]
India
Andhra
Peers
$ cut -f2 funpal.txt [Enter]
Delhi
Hyderabad
Netwc: It will count number of lines, worlds, characters in a file.
Syntax:
$ wc [-option] filename
options:
-l count number of lines
-w count number of words
-c count number of characters
Ex:
$ wc -l paypal.txt
$ wc -w paypal.txt
$ wc -c paypal.txtuniq: This filter is used to get the uniq or duplicate lines from a file. Data should be in order.
Syntax: $ uniq [-option] filename
options:
-d Display duplicate lines
-u Display uniq lines
-c Counts number of times each word has occurred in a file
Ex:
$ cat > city.txt
ameerpet
ameerpet
peers
bhel
hyderabad
ameerpet
peers
secunderabad [ctrl+d]
$ sort city.txt> city1.txt
$cat city1.txt Ascending order of data displaying
This command is used for searching a required pattern in a file.
Syntax:
$ grep [- optopn] "search pattern" Filename [redirection symbol newfilename]
Options:
-i Ignores case sensitiveness in searching pattern
-n displays line numbers for those lines which gets matched and un matched with the pattern
-c counts number of times a searching pattern exists and does not exists
-v (verbose) Displays those lines that does not match with the pattern
Example:
$ cat > paypal.txt
welcome to unix
paypal welcomes you
unix multi user os
WELCOME to the world of unix
$ grep "welcome" paypal.txt
$ grep -i "welcome" paypal.txt
$ grep -i -n "welcome" paypal.txt
$ grep -i -c "welcome" paypal.txt
$ grep -i -v "welcome" paypal.txt
$ grep -i -v -n "welcome" paypal.txt > funpal.txt
Sort : Used to arrange numbers/text in ascending/descending order.
* by default it arranges ascending order.
Syntax:
$ sort [-option] [redirection synbol ] filename [redirection synbol] [new filename]
options:
-r Arrange data in reverse or descending order
-n Arrange data in ascending or descending order by considering whole number.
* if n is not used then numbers gets arranged in order based on 1st digit.
Ex1:
$ sort > paypal.txt
6
2
9
1
5
3
$ cat paypal.txt Ascending order
$ sort -r paypal.txt > funpal.txt Descending order
$cat funpal.txt
Ex2:
$ sort >google.txt
176
2165
8
93
-----
------ [ctrl+d]
$cat google.txt It considered first digit
$sort -n google.txt > yahoo.txt It considered whole number.more: This filter command used to display information from multiple files based n page wise.It gives an identification of end of file for first file and beginning of next file.
Syn:
$more [-option] file1,file2,file3, etc...
options:
-p clears the screen and displays next file in the list of files
*note:
Enter key retrieves next file based on %s
spacebar retrieves complete data from next file
Ex: $more - p paypal.txt funpal.txtcut: Used to cut the required text from a file. It can cut the data on the columns and fields.
Syntax:
$ cut [-option] filename [redirection symbol new filename]
-c To cut the data in columns
-f To cut the data in fields that is that data which is separated by tab.
Ex1:
$ cat>paypal.txt
Hyderabad
Secunderabad
Andhra [ctrl+d]
$ cut -c1 paypal.txt [Enter]
H
S
A
$cut -c3 paypal.txt [Enter]
d
c
d
$cut -c1 -3 paypal.txt [Enter]
Hyd
Sec
And
Ex2:
$cat > funpal.txt [Enter]
India Delhi
Andhra Hyderabad
Peers Net
[ctrl+d]
$ cut -f1 funpal.txt [Enter]
India
Andhra
Peers
$ cut -f2 funpal.txt [Enter]
Delhi
Hyderabad
Netwc: It will count number of lines, worlds, characters in a file.
Syntax:
$ wc [-option] filename
options:
-l count number of lines
-w count number of words
-c count number of characters
Ex:
$ wc -l paypal.txt
$ wc -w paypal.txt
$ wc -c paypal.txtuniq: This filter is used to get the uniq or duplicate lines from a file. Data should be in order.
Syntax: $ uniq [-option] filename
options:
-d Display duplicate lines
-u Display uniq lines
-c Counts number of times each word has occurred in a file
Ex:
$ cat > city.txt
ameerpet
ameerpet
peers
bhel
hyderabad
ameerpet
peers
secunderabad [ctrl+d]
$ sort city.txt> city1.txt
$cat city1.txt Ascending order of data displaying
$ uniq -u city1.txt
$ uniq -d city1.txt
$ uniq -c city1.txt
$ uniq -d city1.txt
$ uniq -c city1.txt
Unix File compare commands
· cmp
· diff
· comm
cmp: It compares 2 files. If files are same it returns prompt or else it returns the message where the difference encountered.
Syn: $ cmp file1 file2
Ex: $ cmp paypal.txt funpal.txtdiff: This command compares 2files like cmp. If any difference found in 2 files it displays those lines.
Ex:
$ diff paypal.txt funpal.txt comm : Used to compare 2 sorted files .It provides output in 3 columns.
* In first column displays uniq lines of first file.
* In second column displays uniq lines of second file
* In third column displays common lines in 2 files.
Ex:-
Step1 : Create two files with some data
$ cat> paypal.txt
risk
payments
ebay
uv
norkom
$ cat> funpal.txt
foodball
cricket
crems
ebay
payments
Step2: Sort above files and store the data into another 2 different files
$ sort paypal.txt paypal1.txt [Enter]
$ sort funpal.txt funpal1.txt [Enter]
Step3: Use comm command
$ comm paypal1.txt funpal1.txt [Enter]
** output shows in 3 different columns.
Syn: $ cmp file1 file2
Ex: $ cmp paypal.txt funpal.txtdiff: This command compares 2files like cmp. If any difference found in 2 files it displays those lines.
Ex:
$ diff paypal.txt funpal.txt comm : Used to compare 2 sorted files .It provides output in 3 columns.
* In first column displays uniq lines of first file.
* In second column displays uniq lines of second file
* In third column displays common lines in 2 files.
Ex:-
Step1 : Create two files with some data
$ cat> paypal.txt
risk
payments
ebay
uv
norkom
$ cat> funpal.txt
foodball
cricket
crems
ebay
payments
Step2: Sort above files and store the data into another 2 different files
$ sort paypal.txt paypal1.txt [Enter]
$ sort funpal.txt funpal1.txt [Enter]
Step3: Use comm command
$ comm paypal1.txt funpal1.txt [Enter]
** output shows in 3 different columns.
FAQ’s
1) How to find hidden files in current directory?
$ ls -a2) How to find current running processes in Unix server?
$ ps -ef
and if we want to find specific process we can use 'grep' with pipe
$ ps -ef | grep -i 'application'3) How to find process which is taking maximum memory in server?
$ top
top command tell us about cpu usage , process id and other details.
$ ls -a2) How to find current running processes in Unix server?
$ ps -ef
and if we want to find specific process we can use 'grep' with pipe
$ ps -ef | grep -i 'application'3) How to find process which is taking maximum memory in server?
$ top
top command tell us about cpu usage , process id and other details.
4) How to find Exception in log files available in current directory and how to find number of occurrence?
$ grep 'Exception' log1.txt | wc -l5) find all files in current and subdirectories which contains 'log' name?
$ find . -name 'log'6) How do you access command line arguments from within a shell script?
$ grep 'Exception' log1.txt | wc -l5) find all files in current and subdirectories which contains 'log' name?
$ find . -name 'log'6) How do you access command line arguments from within a shell script?
Arguments passed from the command line to a shell script can be accessed within the shell script by using a $ (dollar sign) immediately followed with the argument's numeric position on the command line.
7) How to tails last 200 lines of any log fine?
$ tail -200f filename.txt
8) How to find remaining disk space in unix/linux server?
$ df -kl
9) How to make any script file executable?
$chmod 755 *.sh
10) How to kill process in unix server?
$ kill -9 #pid
these #pid can be found using ps -ef command.
10) How to kill process in unix server?
$ kill -9 #pid
these #pid can be found using ps -ef command.
11) Command to run a job say job.sh in background?
.job.sh &
12) How to check a process named Informatica is running or not?
Ps –ef|grep Informatica
13) Command to force any process to stop execution?
Kill -9 pid (process id)
14) Command to get the present directory you are working?
Pwd
15) Ipconfig equivalent in unix or command which gives all the network related details?
Ifconfig
