1.
What is
Linux alias Command?
Explanation
|
||||
alias COMMAND: alias command allows you to create a shortcut to a command. As the name indicates, you can set alias/shortcut name for the commands/paths which is too longer to remember. SYNTAX: The Syntax is alias [options] [ AliasName [ =String ] ] OPTIONS:
EXAMPLE:
1. To create
a shortcut temporarily:
alias lhost='cd /var/www/html'
This command will set lhost to cd
/var/www/html/.
Now if you type lhost it will take you to the specified folder/directory.
2. To
create a shortcut Permanently:
You can put your aliases into the /home/user/.bashrc file. It is good to add them at the end of the file.
alias home='cd
/var/www/html/hscripts/linux-commands'
Now if you type home it will take you to the
specified folder/directory.
3. To
create a shortcut for a command:
alias c='clear'
This command will set c to clear.
Now if you type c it will clear the screen. |
2.
What is
Linux awk Command?
Explanation
|
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awk COMMAND: awk command is used to manipulate the text.This command checks each line of a file, looking for patterns that match those given on the command line. SYNTAX: The Syntax is awk '{pattern + action}' {filenames} OPTIONS:
EXAMPLE: Lets create a file file1.txt and let it have the following data:
1. To
print the second column data in file1.txt
awk '{print $2}' file1.txt
This command will manipulate and print
second column of text file (file1.txt). The output will look like
15
15 56 25
2. To
multiply the column-1 and column-2 and redirect the output to file2.txt:
awk '{print $1,$2,$1*$2}' file1.txt >
file2.txt
The above command will redirect the output to file2.txt and it will look like, 14 15 210 15 15 225 5 56 280 5 25 125 |
3. What is Linux autoreconf Command?
Explanation
|
||||||||||||||||||||||||||||||||||
autoreconf COMMAND: autoreconf - Update generated configuration files Run 'autoreconf' repeatedly to remake the GNU Build System files in the DIRECTORIES or the directory trees driven by CONFIG-URE-AC. By default, it only remakes those files that are older than their predecessors. If you install new versions of the GNU Build System, running 'autoreconf' remakes all of the files by giving it the '--force' option. SYNTAX: The Syntax is autoreconf [OPTION] ... [CONFIGURE-AC or DIRECTORY] ... OPTIONS:
EXAMPLE:
|
4. What is Linux a2p Command?
Explanation
|
||||||||||
a2p COMMAND: a2p - Awk to Perl translator A2p takes an awk script specified on the command line (or from standard input) and produces a comparable perl script on the standard output. SYNTAX: The Syntax is a2p [options] [filename] OPTIONS:
EXAMPLE:
Awk to perl translator scripts are often embedded in a shell script that pipes stuff into and out of awk. Often the shell script wrapper can be incorporated into the perl script, since perl can start up pipes into and out of itself, and can do other things that awk can't do by itself. |
5. What is Linux bc Command?
Explanation
|
||||||
bc COMMAND: bc command is used for command line calculator. It is similar to basic calculator. By using which we can do basic mathematical calculations. SYNTAX: The Syntax is bc [options] OPTIONS:
EXAMPLE:
1. bc
Output:
bc 1.06
Copyright 1991-1994,1997,1998,2000 Free
Software Foundation,Inc.
This is free software with ABSOLUTELY NO
WARRANTY.
For details type `warranty'.
9*2
18
The above command used is for mathematical
calculations.
2. bc -l
Output:
bc 1.06
Copyright 1991-1994,1997,1998,2000 Free
Software Foundation,Inc.
This is free software with ABSOLUTELY NO
WARRANTY.
For details type `warranty'.
1+2
3
The above command displays the sum of '1+2'.
3. bc calc.txt
Output:
bc 1.06
Copyright 1991-1994,1997,1998,2000 Free
Software Foundation,Inc.
This is free software with ABSOLUTELY NO
WARRANTY.
For details type `warranty'.
3
'calc.txt' file have the following code:1+2.
Get the input from file and displays the output.
|
6. What is Linux bg Command
Explanation
|
||||||||
bg COMMAND: bg command is used to place a job in background. User can run a job in the background by adding a "&" symbol at the end of the command. SYNTAX: The Syntax is bg [options] [job] OPTIONS:
EXAMPLE:
1. To
Run a process in background
2. kmail- start the email client application.
Press ctrl+z to stop the current job.
Now just type bg to
move last stopped job to background.
3. To
move the specified job to back ground:
Lets start some three jobs and suspend those
process in background.
kmail- start the email client application.
Press ctrl+z to stop the current job.
xmms- music player application.
Press ctrl+z to stop the current job.
sleep 120- a dummy job.
Press ctrl+z to stop the current job.
jobs
The above command will display the jobs in
the shell.
[1]
Stopped kmail
[2]-
Stopped xmms
[3]+
Stopped sleep
120
bg 2
The above command will start running the
xmms application. In such way you can start running the specific background
process.
jobs
[1]-
Stopped kmail
[2]
Running xmms
&
[3]+
Stopped sleep
120
|
7. What is Linux bzip2 Command?
Explanation
|
||||||||||||||||||||||||||||
bzip2 COMMAND: bzip2 linux command is used to compress the file. Each file is replaced by a compressed version of itself with .bz2 extension. SYNTAX: The Syntax is bzip2 [ options ] filenames OPTIONS:
EXAMPLE:
1. To
Compress a file using bzip2:
Lets have a text file as an example.
$ ls -l
-rw-rw-r--
1 hiox hiox 9150000 Sep 26 18:37 hiox.txt
$ bzip2 -c -1 hiox.txt > hiox.txt.bz2
$ ls -l
-rw-rw-r--
1 hiox hiox 9150000 Sep 26 18:37 hiox.txt
-rw-rw-r--
1 hiox hiox 17706 Sep 27 12:38
hiox.txt.bz2
From the above example it is clear that the
filesize is reduced from 9150000 bytes to 17706.
When the File is reduced with option -9 the
filesize still gets reduced.
$ bzip2 -c -9 hiox.txt > hscripts.txt.bz2
$ ls -l
-rw-rw-r--
1 hiox hiox 9150000 Sep 26 18:37 hiox.txt
-rw-rw-r--
1 hiox hiox 17706 Sep 27 12:38
hiox.txt.bz2
-rw-rw-r--
1 hiox hiox 2394 Sep 27 13:01
hscripts.txt.bz2
When the file is compressed with -1 the size
was 17706 bytes and now the filesize is 2394 bytes. The 9 makes best
compression but the default is 6.
|
8. What is Linux cal Command?
Explanation
|
||||||||||||
cal COMMAND: cal command is used to display the calendar. SYNTAX: The Syntax is cal [options] [month] [year] OPTIONS:
EXAMPLE:
1. cal
Output:
September 2008
Su Mo Tu We Th Fr Sa
1 2 3
4 5 6
7
8 9 10 11 12 13
14 15 16 17 18 19 20
21 22 23 24 25 26 27
28 29 30
cal command displays the current month
calendar.
2. cal -3 5 2008
Output:
April 2008 May
2008 June 2008
Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa
1 2 3
4 5 1 2
3 1 2
3 4 5
6 7
6
7 8 9 10 11 12
4 5 6
7 8 9 10
8 9 10 11 12 13 14
13 14 15 16 17 18 19 11 12 13 14 15 16 17 15 16 17 18 19 20 21
20 21 22 23 24 25 26 18 19 20 21 22 23 24 22 23 24 25 26 27 28
27 28 29 30 25 26 27 28 29 30 31 29 30
Here the cal command displays the calendar
of April, May and June month of year 2008.
|
9. What is Linux cat Command?
Explanation
|
||||||||||||||||
cat COMMAND: cat linux command concatenates files and print it on the standard output. SYNTAX: The Syntax is cat [OPTIONS] [FILE]... OPTIONS:
EXAMPLE:
1. To
Create a new file:
cat > file1.txt
This command creates a new file file1.txt.
After typing into the file press control+d (^d) simultaneously to end the
file.
2. To
Append data into the file:
cat >> file1.txt
To append data into the same file use append
operator >> to write into the file, else the file will be overwritten
(i.e., all of its contents will be erased).
3. To
display a file:
cat file1.txt
This command displays the data in the file.
4. To
concatenate several files and display:
cat file1.txt file2.txt
The above cat command will concatenate the
two files (file1.txt and file2.txt) and it will display the output in the
screen. Some times the output may not fit the monitor screen. In such
situation you can print those files in a new file or display the file using
less command.
cat file1.txt file2.txt | less
5. To
concatenate several files and to transfer the output to another file.
cat file1.txt file2.txt > file3.txt
In the above example the output is
redirected to new file file3.txt. The cat command will create new file
file3.txt and store the concatenated output into file3.txt.
|
Create a new tar archive.
$
tar cvf archive_name.tar dirname/
Extract from an existing tar archive.
$
tar xvf archive_name.tar
View an existing tar archive.
$
tar tvf archive_name.tar
More tar examples:
2. grep command examples
Search for a given string in a file (case in-sensitive search).
$
grep -i "the" demo_file
Print the matched line, along with the 3 lines after it.
$
grep -A 3 -i "example" demo_text
Search for a given string in all files recursively
$
grep -r "ramesh" *
3. find command examples
Find files using file-name ( case in-sensitve find)
#
find -iname "MyCProgram.c"
Execute commands on files found by the find command
$
find -iname "MyCProgram.c" -exec md5sum {} \;
Find all empty files in home directory
#
find ~ -empty
4. ssh command examples
Login to remote host
ssh
-l jsmith remotehost.example.com
Debug ssh client
ssh
-v -l jsmith remotehost.example.com
Display ssh client version
$
ssh -V
OpenSSH_3.9p1,
OpenSSL 0.9.7a Feb 19 2003
5. sed command examples
When you copy a DOS file to Unix, you could find \r\n in the end
of each line. This example converts the DOS file format to Unix file format
using sed command.
$sed
's/.$//' filename
Print file content in reverse order
$
sed -n '1!G;h;$p' thegeekstuff.txt
Add line number for all non-empty-lines in a file
$
sed '/./=' thegeekstuff.txt | sed 'N; s/\n/ /'
6. awk command examples
Remove duplicate lines using awk
$
awk '!($0 in array) { array[$0]; print }' temp
Print all lines from /etc/passwd that has the same uid and gid
$awk
-F ':' '$3==$4' passwd.txt
Print only specific field from a file.
$
awk '{print $2,$5;}' employee.txt
7. vim command examples
Go to the 143rd line of file
$
vim +143 filename.txt
Go to the first match of the specified
$
vim +/search-term filename.txt
Open the file in read only mode.
$
vim -R /etc/passwd
8. diff command examples
Ignore white space while comparing.
#
diff -w name_list.txt name_list_new.txt
2c2,3
<
John Doe --- > John M Doe
>
Jason Bourne
9. sort command examples
Sort a file in ascending order
$
sort names.txt
Sort a file in descending order
$
sort -r names.txt
Sort passwd file by 3rd field.
$
sort -t: -k 3n /etc/passwd | more
10. export command examples
To view oracle related environment variables.
$
export | grep ORACLE
declare
-x ORACLE_BASE="/u01/app/oracle"
declare
-x ORACLE_HOME="/u01/app/oracle/product/10.2.0"
declare
-x ORACLE_SID="med"
declare
-x ORACLE_TERM="xterm"
To export an environment variable:
$
export ORACLE_HOME=/u01/app/oracle/product/10.2.0
11. xargs command examples
Copy all images to external hard-drive
#
ls *.jpg | xargs -n1 -i cp {} /external-hard-drive/directory
Search all jpg images in the system and archive it.
#
find / -name *.jpg -type f -print | xargs tar -cvzf images.tar.gz
Download all the URLs mentioned in the url-list.txt file
#
cat url-list.txt | xargs wget –c
12. ls command examples
Display filesize in human readable format (e.g. KB, MB etc.,)
$
ls -lh
-rw-r-----
1 ramesh team-dev 8.9M Jun 12 15:27 arch-linux.txt.gz
Order Files Based on Last Modified Time (In Reverse Order) Using
ls -ltr
$
ls -ltr
Visual Classification of Files With Special Characters Using ls
-F
$
ls -F
13. pwd command
pwd is Print working directory. What else can be said about the
good old pwd who has been printing the current directory name for ages.
14. cd command examples
Use “cd -” to toggle between the last two directories
Use “shopt -s cdspell” to automatically correct mistyped
directory names on cd
15. gzip command examples
To create a *.gz compressed file:
$
gzip test.txt
To uncompress a *.gz file:
$
gzip -d test.txt.gz
Display compression ratio of the compressed file using gzip -l
$
gzip -l *.gz
compressed uncompressed ratio uncompressed_name
23709 97975 75.8% asp-patch-rpms.txt
16. bzip2 command examples
To create a *.bz2 compressed file:
$
bzip2 test.txt
To uncompress a *.bz2 file:
bzip2
-d test.txt.bz2
More bzip2 examples:
17. unzip command examples
To extract a *.zip compressed file:
$
unzip test.zip
View the contents of *.zip file (Without unzipping it):
$
unzip -l jasper.zip
Archive: jasper.zip
Length
Date Time Name
--------
---- ---- ----
40995
11-30-98 23:50
META-INF/MANIFEST.MF
32169
08-25-98 21:07 classes_
15964
08-25-98 21:07 classes_names
10542
08-25-98 21:07 classes_ncomp
18. shutdown command examples
Shutdown the system and turn the power off immediately.
#
shutdown -h now
Shutdown the system after 10 minutes.
#
shutdown -h +10
Reboot the system using shutdown command.
#
shutdown -r now
Force the filesystem check during reboot.
#
shutdown -Fr now
19. ftp command examples
Both ftp and secure ftp (sftp) has similar commands. To connect
to a remote server and download multiple files, do the following.
$
ftp IP/hostname
ftp>
mget *.html
To view the file names located on the remote server before
downloading, mls ftp command as shown below.
ftp>
mls *.html -
/ftptest/features.html
/ftptest/index.html
/ftptest/othertools.html
/ftptest/samplereport.html
/ftptest/usage.html
More ftp examples:
20. crontab command examples
View crontab entry for a specific user
#
crontab -u john -l
Schedule a cron job every 10 minutes.
*/10
* * * * /home/ramesh/check-disk-space
More crontab examples:
21. service command examples
Service command is used to run the system V init scripts. i.e
Instead of calling the scripts located in the /etc/init.d/ directory with their
full path, you can use the service command.
Check the status of a service:
#
service ssh status
Check the steatus of all the services.
service
--status-all
Restart a service.
#
service ssh restart
22. ps command examples
ps command is used to display information about the processes
that are running in the system.
While there are lot of arguments that could be passed to a ps
command, following are some of the common ones.
To view current running processes.
$
ps -ef | more
To view current running processes in a tree structure. H option
stands for process hierarchy.
$
ps -efH | more
23. free command examples
This command is used to display the free, used, swap memory
available in the system.
Typical free command output. The output is displayed in bytes.
$
free
total used free
shared buffers cached
Mem: 3566408 1580220
1986188 0 203988
902960
-/+
buffers/cache: 473272 3093136
Swap: 4000176 0
4000176
If you want to quickly check how many GB of RAM your system has
use the -g option. -b option displays in bytes, -k in kilo bytes, -m in mega
bytes.
$
free -g
total used
free shared buffers
cached
Mem: 3 1 1 0 0 0
-/+
buffers/cache: 0 2
Swap: 3 0 3
If you want to see a total memory ( including the swap), use the
-t switch, which will display a total line as shown below.
ramesh@ramesh-laptop:~$
free -t
total used free
shared buffers cached
Mem: 3566408 1592148
1974260 0 204260
912556
-/+
buffers/cache: 475332 3091076
Swap: 4000176 0
4000176
Total: 7566584
1592148 5974436
24. top command examples
top command displays the top processes in the system ( by
default sorted by cpu usage ). To sort top output by any column, Press O
(upper-case O) , which will display all the possible columns that you can sort
by as shown below.
Current
Sort Field: P for window 1:Def
Select
sort field via field letter, type any other key to return
a: PID
= Process Id v:
nDRT = Dirty Pages count
d: UID
= User Id y:
WCHAN = Sleeping in Function
e: USER
= User Name z:
Flags = Task Flags
........
To displays only the processes that belong to a particular user
use -u option. The following will show only the top processes that belongs to
oracle user.
$
top -u oracle
25. df command examples
Displays the file system disk space usage. By default df -k
displays output in bytes.
$
df -k
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sda1 29530400 3233104
24797232 12% /
/dev/sda2 120367992 50171596
64082060 44% /home
df -h displays output in human readable form. i.e size will be
displayed in GB’s.
ramesh@ramesh-laptop:~$
df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda1 29G 3.1G
24G 12% /
/dev/sda2 115G 48G
62G 44% /home
Use -T option to display what type of file system.
ramesh@ramesh-laptop:~$
df -T
Filesystem Type
1K-blocks Used Available Use%
Mounted on
/dev/sda1 ext4
29530400 3233120 24797216
12% /
/dev/sda2 ext4
120367992 50171596 64082060
44% /home
26. kill command examples
Use kill command to terminate a process. First get the process
id using ps -ef command, then use kill -9 to kill the running Linux process as
shown below. You can also use killall, pkill, xkill to terminate a unix
process.
$
ps -ef | grep vim
ramesh 7243
7222 9 22:43 pts/2 00:00:00 vim
$
kill -9 7243
27. rm command examples
Get confirmation before removing the file.
$
rm -i filename.txt
It is very useful while giving shell metacharacters in the file
name argument.
Print the filename and get confirmation before removing the
file.
$
rm -i file*
Following example recursively removes all files and directories
under the example directory. This also removes the example directory itself.
$
rm -r example
28. cp command examples
Copy file1 to file2 preserving the mode, ownership and
timestamp.
$
cp -p file1 file2
Copy file1 to file2. if file2 exists prompt for confirmation
before overwritting it.
$
cp -i file1 file2
29. mv command examples
Rename file1 to file2. if file2 exists prompt for confirmation
before overwritting it.
$
mv -i file1 file2
Note: mv -f is just the opposite, which will overwrite file2
without prompting.
mv -v will print what is happening during file rename, which is
useful while specifying shell metacharacters in the file name argument.
$
mv -v file1 file2
30. cat command examples
You can view multiple files at the same time. Following example
prints the content of file1 followed by file2 to stdout.
$
cat file1 file2
While displaying the file, following cat -n command will prepend
the line number to each line of the output.
$
cat -n /etc/logrotate.conf
1 /var/log/btmp
{
2 missingok
3 monthly
4 create 0660 root utmp
5 rotate 1
6 }
31. mount command examples
To mount a file system, you should first create a directory and
mount it as shown below.
#
mkdir /u01
#
mount /dev/sdb1 /u01
You can also add this to the fstab for automatic mounting. i.e
Anytime system is restarted, the filesystem will be mounted.
/dev/sdb1
/u01 ext2 defaults 0 2
32. chmod command examples
chmod command is used to change the permissions for a file or
directory.
Give full access to user and group (i.e read, write and execute
) on a specific file.
$
chmod ug+rwx file.txt
Revoke all access for the group (i.e read, write and execute )
on a specific file.
$
chmod g-rwx file.txt
Apply the file permissions recursively to all the files in the
sub-directories.
$
chmod -R ug+rwx file.txt
33. chown command examples
chown command is used to change the owner and group of a file. \
To change owner to oracle and group to db on a file. i.e Change
both owner and group at the same time.
$
chown oracle:dba dbora.sh
Use -R to change the ownership recursively.
$
chown -R oracle:dba /home/oracle
34. passwd command examples
Change your password from command line using passwd. This will
prompt for the old password followed by the new password.
$
passwd
Super user can use passwd command to reset others password. This
will not prompt for current password of the user.
#
passwd USERNAME
Remove password for a specific user. Root user can disable
password for a specific user. Once the password is disabled, the user can login
without entering the password.
#
passwd -d USERNAME
35. mkdir command examples
Following example creates a directory called temp under your
home directory.
$
mkdir ~/temp
Create nested directories using one mkdir command. If any of
these directories exist already, it will not display any error. If any of these
directories doesn’t exist, it will create them.
$
mkdir -p dir1/dir2/dir3/dir4/
36. ifconfig command examples
Use ifconfig command to view or configure a network interface on
the Linux system.
View all the interfaces along with status.
$
ifconfig -a
Start or stop a specific interface using up and down command as
shown below.
$
ifconfig eth0 up
$
ifconfig eth0 down
37. uname command examples
Uname command displays important information about the system
such as — Kernel name, Host name, Kernel release number,
Processor type, etc.,
Processor type, etc.,
Sample uname output from a Ubuntu laptop is shown below.
$
uname -a
Linux
john-laptop 2.6.32-24-generic #41-Ubuntu SMP Thu Aug 19 01:12:52 UTC 2010 i686
GNU/Linux
38. whereis command examples
When you want to find out where a specific Unix command exists
(for example, where does ls command exists?), you can execute the following
command.
$
whereis ls
ls:
/bin/ls /usr/share/man/man1/ls.1.gz /usr/share/man/man1p/ls.1p.gz
When you want to search an executable from a path other than the
whereis default path, you can use -B option and give path as argument to it.
This searches for the executable lsmk in the /tmp directory, and displays it,
if it is available.
$
whereis -u -B /tmp -f lsmk
lsmk:
/tmp/lsmk
39. whatis command examples
Whatis command displays a single line description about a
command.
$
whatis ls
ls (1)
- list directory contents
$
whatis ifconfig
ifconfig
(8) - configure a network
interface
40. locate command examples
Using locate command you can quickly search for the location of
a specific file (or group of files). Locate command uses the database created
by updatedb.
The example below shows all files in the system that contains
the word crontab in it.
$
locate crontab
/etc/anacrontab
/etc/crontab
/usr/bin/crontab
/usr/share/doc/cron/examples/crontab2english.pl.gz
/usr/share/man/man1/crontab.1.gz
/usr/share/man/man5/anacrontab.5.gz
/usr/share/man/man5/crontab.5.gz
/usr/share/vim/vim72/syntax/crontab.vim
41. man command examples
Display the man page of a specific command.
$
man crontab
When a man page for a command is located under more than one
section, you can view the man page for that command from a specific section as
shown below.
$
man SECTION-NUMBER commandname
Following 8 sections are available in the man page.
1. General
commands
2. System calls
3. C library
functions
4. Special files
(usually devices, those found in /dev) and drivers
5. File formats
and conventions
6. Games and
screensavers
7. Miscellaneous
8. System
administration commands and daemons
For example, when you do whatis crontab, you’ll notice that
crontab has two man pages (section 1 and section 5). To view section 5 of
crontab man page, do the following.
$
whatis crontab
crontab
(1) - maintain crontab files for
individual users (V3)
crontab
(5) - tables for driving cron
$
man 5 crontab
42. tail command examples
Print the last 10 lines of a file by default.
$
tail filename.txt
Print N number of lines from the file named filename.txt
$
tail -n N filename.txt
View the content of the file in real time using tail -f. This is
useful to view the log files, that keeps growing. The command can be terminated
using CTRL-C.
$
tail -f log-file
43. less command examples
less is very efficient while viewing huge log files, as it
doesn’t need to load the full file while opening.
$
less huge-log-file.log
One you open a file using less command, following two keys are
very helpful.
CTRL+F
– forward one window
CTRL+B
– backward one window
44. su command examples
Switch to a different user account using su command. Super user
can switch to any other user without entering their password.
$
su - USERNAME
Execute a single command from a different account name. In the
following example, john can execute the ls command as raj username. Once the
command is executed, it will come back to john’s account.
[john@dev-server]$
su - raj -c 'ls'
[john@dev-server]$
Login to a specified user account, and execute the specified
shell instead of the default shell.
$
su -s 'SHELLNAME' USERNAME
45. mysql command examples
mysql is probably the most widely used open source database on
Linux. Even if you don’t run a mysql database on your server, you might end-up
using the mysql command ( client ) to connect to a mysql database running on
the remote server.
To connect to a remote mysql database. This will prompt for a
password.
$
mysql -u root -p -h 192.168.1.2
To connect to a local mysql database.
$
mysql -u root -p
If you want to specify the mysql root password in the command
line itself, enter it immediately after -p (without any space).
46. yum command examples
To install apache using yum.
$
yum install httpd
To upgrade apache using yum.
$
yum update httpd
To uninstall/remove apache using yum.
$
yum remove httpd
47. rpm command examples
To install apache using rpm.
#
rpm -ivh httpd-2.2.3-22.0.1.el5.i386.rpm
To upgrade apache using rpm.
#
rpm -uvh httpd-2.2.3-22.0.1.el5.i386.rpm
To uninstall/remove apache using rpm.
#
rpm -ev httpd
48. ping command examples
Ping a remote host by sending only 5 packets.
$
ping -c 5 gmail.com
49. date command examples
Set the system date:
#
date -s "01/31/2010 23:59:53"
Once you’ve changed the system date, you should syncronize the
hardware clock with the system date as shown below.
#
hwclock –systohc
#
hwclock --systohc –utc
50. wget command examples
The quick and effective method to download software, music,
video from internet is using wget command.
$
wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.2.1.tar.gz
Download and store it with a different name.
$
wget -O taglist.zip http://www.vim.org/scripts/download_script.php?src_id=7701