Basic Commands for Managing Linux Servers

This article will provide an introduction to some basic commands that you can use to manage your Linux server via Shell.

For all linux commands, you can press the button twice "tab" to see the possibility of commands that can be used. For example if you want to know any command that begins with the initial letter co, then simply type c and press "tab" twice, the command-command beginning with the letter co will appear.

# co  2x
col            colrm          comm           compgen        complete       consoletype
colcrt         column         command        compile_et     consolehelper  continue

Help

Each command usually has a parameter that we can use, we know this can easily by typing additional (space)-help in order that we want to learn more.

# ps --help
********* simple selection *********  ********* selection by list *********
-A all processes                      -C by command name
-N negate selection                   -G by real group ID (supports names)
-a all w/ tty except session leaders  -U by real user ID (supports names)
...
dan seterusnya

Pipe(|)

Pipe (|) can be used to combine two or more commands to achieve the output that we want, different commands are adequately separated by symbol "|".

For example if we want we can split the output from the command listing (ls), which is more than one page, we can use the command more, this will stop the display perhalaman. Or we want to filter the output of ps, for example just want to show a line that has the word nginx, it can be done using grep;

# ps aux | grep nginx
root     10148  0.0  0.3  42948  1012 ?        Ss   21:42   0:00 nginx: master process /usr/local/sbin/nginx
nobody   10149  0.0  0.8  43848  2316 ?        S    21:42   0:00 nginx: worker process
nobody   10150  0.0  0.8  43716  2196 ?        S    21:42   0:00 nginx: worker process
nobody   10151  0.0  0.9  43956  2424 ?        S    21:42   0:00 nginx: worker process
nobody   10152  0.0  0.5  43324  1444 ?        S    21:42   0:00 nginx: worker process
nobody   10153  0.0  0.8  44120  2308 ?        S    21:42   0:00 nginx: worker process
root     11328  0.0  0.2   5996   540 pts/0    R+   22:41   0:00 grep nginx

df

Used to view information filesystems on each partition. But commonly used is the df-h because it looks easily understood by us, some other parameters can be used to change preferences that you want.

# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda1              40G   17G   21G  46% /
varrun                 512M   84K  512M   1% /var/run
varlock                512M     0  512M   0% /var/lock
udev                   512M   16K  512M   1% /dev
devshm               512M     0  512M   0% /dev/shm
none                   512M     0  512M   0% /dev/shm

ps

ps is the command used if we need to check the processes running on the server. Examples of the ps command is ps-aux basis, because all running processes will appear. If we only want to see a process (eg Apache), then use the command ps-aux | grep apache.
top

Displays system statistics and details of the process in an active server.

w

To see who is logged on the server

netstat

Displays a summary of the status of network connections and sockets that are running on the server. We can specialize to a particular port (eg port 80), then the command to use is netstat | grep: 80
yum / apt-get

yum is a package manipulation commands that are typically used by rpm-based Linux distributions like Red Hat, CentOS and Fedora, while apt-get is used by debian-based Linux distributions like Debian and Ubuntu. Manipulation of files with the package management will greatly depend on the used Linux distribution.

To install or update package, can use the command:

$ 
yum install "packet name"
$ apt-get install "paket name"

Or if we need to update packet, can use the command:

$ yum update "paket name"

Atau untuk mencari paket yang tersedia sesuai dengan keyword yang kita masukkan dapat dilakukan dengan cara;

$ yum search keyword

free

Digunakan untuk melihat sisa memory dan swap yang terpakai, umumnya digunakan free -m yaitu mengecek memory dengan satuan MB. Contoh penggunaan:

# free -m
total       used       free     shared    buffers     cached
Mem:          1024        387        636          0        154         98
-/+ buffers/cache:        135        888
Swap:         2047          0       2047

wget

Can be used to download files, grab the website, mirroring, etc.. The following examples of use

Downloading files from the server:

$ wget http://www.goldendrake.web.id/contoh.txt

Downloading with meresume system files:

$ wget -c http://www.goldendrake.web.id/contoh.txt

Downloading and used as background, so that we can do something else while the file downloaded:

$ wget -b http://www.goldendrake.web.id/contoh.txt

kill

As the name suggests, this command is used to kill or stop a process. Usually before using kill, then first we run the ps command to see the ID process that wants to kill.

$ ps aux | grep apache2
www-data  9576  0.0  0.2  11272  2156 ?        S    Sep06   0:00 /usr/sbin/apache2 -k start
www-data  9577  0.0  0.1  11456  2020 ?        S    Sep06   0:00 /usr/sbin/apache2 -k start
www-data  9578  0.0  0.3 185916  3588 ?        Sl   Sep06   0:00 /usr/sbin/apache2 -k start
www-data 10523  0.0  0.3 185912  3596 ?        Sl   Sep06   0:00 /usr/sbin/apache2 -k start

Then to stop the process, we type the command kill -9 accompanied by [the means of execution] and PID id:

$ kill -9 1537

ifconfig

This command is used to view IP configuration already exists on the network interface that is on our server. The ifconfig command can also be used to determine the IP address and netmask on an interface. Examples of the use ifconfig to see certain ethernet configuration;

# ifconfig -eth0
eth0    Link encap:Ethernet  HWaddr aa:00:21:fa:62:01
inet addr:117.103.xx.xxx  Bcast:117.103.xx.255  Mask:255.255.255.0
inet6 addr: fe80::a800:21ff:fefa:6201/64 Scope:Link
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
RX packets:3052329 errors:0 dropped:0 overruns:0 frame:0
TX packets:123389 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:895150664 (853.6 MB)  TX bytes:20386246 (19.4 MB)

last

This command is used to see people who logged in last.

# last
test   pts/0        117.103.52.34    Mon Sep  7 15:37   still logged in

locate

Used to find files based on file name or by keyword

locate "name file"

tail

Used to display the final pieces of the file.

tail /var/log/messages #melihat 10 baris terakhir dari /var/log/messages
tail -f /var/log/messages # melihat line dari /var/log/messages secara terus menerus

ping

Just like windows, linux can also check the communication between computers in a network through TCP / IP.

ping ip.address/hostname

traceroute

Traceroute is used to test the link connection to a server. This command will display routing TCP / IP packets from our host to the host.

traceroute ip.address/hostname

shutdown

This command is used to shut down or reboot the system.

shutdown-r now # will restart

If we want to turn off the server, then commandnya are:

shutdown -h now

pwd

Used to see where we are in the directory.

#pwd
/home/test

Means we are in the folder / home / test