Author: root

In this guide, we shall bring to light a simple yet important concept in process handling in a Linux system, that is how to completely detach a process from its controlling terminal.

When a process is associated with a terminal, two problems might occur:

1. your controlling terminal is filled with so much output data and error/diagnostic messages.
2. in the event that the terminal is closed, the process together with its child processes will be terminated.

To deal with these two issues, you need to totally detach a process from a controlling terminal. Before we actually move to solve the problem, let us briefly cover how to run processes in the background.

How to Start a Linux Process or Command in Background

If a process is already in execution, such as the tar command example below, simply press Ctrl+Z to stop it then enter the command bg to continue with its execution in the background as a job.

You can view all your background jobs by typing jobs. However, its stdin, stdout, stderr are still joined to the terminal.

$ tar -czf home.tar.gz .
$ bg
$ jobs

You can as well run a process directly from the background using the ampersand, & sign.

$ tar -czf home.tar.gz . &
$ jobs

Take a look at the example below, although the tar command was started as a background job, an error message was still sent to the terminal meaning the process is still connected to the controlling terminal.

$ tar -czf home.tar.gz . &
$ jobs

Keep Linux Processes Running After Exiting Terminal

We will use disown command, it is used after the a process has been launched and put in the background, it’s work is to remove a shell job from the shell’s active list jobs, therefore you will not use fg, bg commands on that particular job anymore.

In addition, when you close the controlling terminal, the job will not hang or send a SIGHUP to any child jobs.

Suggested Read: 5 Ways to Keep Remote SSH Sessions and Processes Running

Let’s take a look at the below example of using diswon bash built-in function.

$ sudo rsync Templates/* /var/www/html/files/ &
$ jobs
$ disown  -h  %1
$ jobs

You can also use nohup command, which also enables a process to continue running in the background when a user exits a shell.

$ nohup tar -czf iso.tar.gz Templates/* &
$ jobs

Detach a Linux Processes From Controlling Terminal

Therefore, to completely detach a process from a controlling terminal, use the command format below, this is more effective for graphical user interface (GUI) applications such as firefox:

$ firefox </dev/null &>/dev/null &

In Linux, /dev/null is a special device file which writes-off (gets rid of) all data written to it, in the command above, input is read from, and output is sent to /dev/null.

Suggested Read: 10 Screen Command Examples to Detach Terminal Sessions

As a concluding remark, provided a process is connected to a controlling terminal, as a user, you will see several output lines of the process data as well as error messages on your terminal. Again, when you close the a controlling terminal, your process and child processes will be terminated.

Importantly, for any questions or remarks on the subject, reach us by using the comment form below.

Source

This is our another ongoing series of packet sniffer tool called tcpdump. Here, we are going to show you how to install tcpdump and then we discuss and cover some useful commands with their practical examples.

tcpdump is a most powerful and widely used command-line packets sniffer or package analyzer tool which is used to capture or filter TCP/IP packets that received or transferred over a network on a specific interface. It is available under most of the Linux/Unix based operating systems. tcpdump also gives us a option to save captured packets in a file for future analysis. It saves the file in a pcap format, that can be viewed by tcpdump command or a open source GUI based tool called Wireshark (Network Protocol Analyzier) that reads tcpdump pcap format files.

How to Install tcpdump in Linux

Many of Linux distributions already shipped with tcpdump tool, if in case you don’t have it on systems, you can install it using following Yum command.

# yum install tcpdump

Once tcpdump tool is installed on systems, you can continue to browse following commands with their examples.

1. Capture Packets from Specific Interface

The command screen will scroll up until you interrupt and when we execute tcpdump command it will captures from all the interfaces, however with -i switch only capture from desire interface.

# tcpdump -i eth0

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
11:33:31.976358 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 3500440357:3500440553, ack 3652628334, win 18760, length 196
11:33:31.976603 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 196, win 64487, length 0
11:33:31.977243 ARP, Request who-has tecmint.com tell 172.16.25.126, length 28
11:33:31.977359 ARP, Reply tecmint.com is-at 00:14:5e:67:26:1d (oui Unknown), length 46
11:33:31.977367 IP 172.16.25.126.54807 > tecmint.com: 4240+ PTR? 125.25.16.172.in-addr.arpa. (44)
11:33:31.977599 IP tecmint.com > 172.16.25.126.54807: 4240 NXDomain 0/1/0 (121)
11:33:31.977742 IP 172.16.25.126.44519 > tecmint.com: 40988+ PTR? 126.25.16.172.in-addr.arpa. (44)
11:33:32.028747 IP 172.16.20.33.netbios-ns > 172.16.31.255.netbios-ns: NBT UDP PACKET(137): QUERY; REQUEST; BROADCAST
11:33:32.112045 IP 172.16.21.153.netbios-ns > 172.16.31.255.netbios-ns: NBT UDP PACKET(137): QUERY; REQUEST; BROADCAST
11:33:32.115606 IP 172.16.21.144.netbios-ns > 172.16.31.255.netbios-ns: NBT UDP PACKET(137): QUERY; REQUEST; BROADCAST
11:33:32.156576 ARP, Request who-has 172.16.16.37 tell old-oraclehp1.midcorp.mid-day.com, length 46
11:33:32.348738 IP tecmint.com > 172.16.25.126.44519: 40988 NXDomain 0/1/0 (121)

2. Capture Only N Number of Packets

When you run tcpdump command it will capture all the packets for specified interface, until you Hit cancel button. But using -c option, you can capture specified number of packets. The below example will only capture 6packets.

# tcpdump -c 5 -i eth0

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
11:40:20.281355 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 3500447285:3500447481, ack 3652629474, win 18760, length 196
11:40:20.281586 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 196, win 65235, length 0
11:40:20.282244 ARP, Request who-has tecmint.com tell 172.16.25.126, length 28
11:40:20.282360 ARP, Reply tecmint.com is-at 00:14:5e:67:26:1d (oui Unknown), length 46
11:40:20.282369 IP 172.16.25.126.53216 > tecmint.com.domain: 49504+ PTR? 125.25.16.172.in-addr.arpa. (44)
11:40:20.332494 IP tecmint.com.netbios-ssn > 172.16.26.17.nimaux: Flags [P.], seq 3058424861:3058424914, ack 693912021, win 64190, length 53 NBT Session Packet: Session Message
6 packets captured
23 packets received by filter
0 packets dropped by kernel

3. Print Captured Packets in ASCII

The below tcpdump command with option -A displays the package in ASCII format. It is a character-encoding scheme format.

# tcpdump -A -i eth0

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
09:31:31.347508 IP 192.168.0.2.ssh > 192.168.0.1.nokia-ann-ch1: Flags [P.], seq 3329372346:3329372542, ack 4193416789, win 17688, length 196
M.r0...vUP.E.X.......~.%..>N..oFk.........KQ..)Eq.d.,....r^l......m\.oyE....-....g~m..Xy.6..1.....c.O.@...o_..J....i.*.....2f.mQH...Q.c...6....9.v.gb........;..4.).UiCY]..9..x.)..Z.XF....'|..E......M..u.5.......ul
09:31:31.347760 IP 192.168.0.1.nokia-ann-ch1 > 192.168.0.2.ssh: Flags [.], ack 196, win 64351, length 0
M....vU.r1~P.._..........
^C09:31:31.349560 IP 192.168.0.2.46393 > b.resolvers.Level3.net.domain: 11148+ PTR? 1.0.168.192.in-addr.arpa. (42)
E..F..@.@............9.5.2.f+............1.0.168.192.in-addr.arpa.....

3 packets captured
11 packets received by filter
0 packets dropped by kernel

4. Display Available Interfaces

To list number of available interfaces on the system, run the following command with -D option.

# tcpdump -D

 1.eth0
2.eth1
3.usbmon1 (USB bus number 1)
4.usbmon2 (USB bus number 2)
5.usbmon3 (USB bus number 3)
6.usbmon4 (USB bus number 4)
7.usbmon5 (USB bus number 5)
8.any (Pseudo-device that captures on all interfaces)
9.lo

5. Display Captured Packets in HEX and ASCII

The following command with option -XX capture the data of each packet, including its link level header in HEXand ASCII format.

# tcpdump -XX -i eth0

11:51:18.974360 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 3509235537:3509235733, ack 3652638190, win 18760, length 196
        0x0000:  b8ac 6f2e 57b3 0001 6c99 1468 0800 4510  ..o.W...l..h..E.
        0x0010:  00ec 8783 4000 4006 275d ac10 197e ac10  ....@.@.']...~..
        0x0020:  197d 0016 1129 d12a af51 d9b6 d5ee 5018  .}...).*.Q....P.
        0x0030:  4948 8bfa 0000 0e12 ea4d 22d1 67c0 f123  IH.......M".g..#
        0x0040:  9013 8f68 aa70 29f3 2efc c512 5660 4fe8  ...h.p).....V`O.
        0x0050:  590a d631 f939 dd06 e36a 69ed cac2 95b6  Y..1.9...ji.....
        0x0060:  f8ba b42a 344b 8e56 a5c4 b3a2 ed82 c3a1  ...*4K.V........
        0x0070:  80c8 7980 11ac 9bd7 5b01 18d5 8180 4536  ..y.....[.....E6
        0x0080:  30fd 4f6d 4190 f66f 2e24 e877 ed23 8eb0  0.OmA..o.$.w.#..
        0x0090:  5a1d f3ec 4be4 e0fb 8553 7c85 17d9 866f  Z...K....S|....o
        0x00a0:  c279 0d9c 8f9d 445b 7b01 81eb 1b63 7f12  .y....D[{....c..
        0x00b0:  71b3 1357 52c7 cf00 95c6 c9f6 63b1 ca51  q..WR.......c..Q
        0x00c0:  0ac6 456e 0620 38e6 10cb 6139 fb2a a756  ..En..8...a9.*.V
        0x00d0:  37d6 c5f3 f5f3 d8e8 3316 d14f d7ab fd93  7.......3..O....
        0x00e0:  1137 61c1 6a5c b4d1 ddda 380a f782 d983  .7a.j\....8.....
        0x00f0:  62ff a5a9 bb39 4f80 668a                 b....9O.f.
11:51:18.974759 IP 172.16.25.126.60952 > mddc-01.midcorp.mid-day.com.domain: 14620+ PTR? 125.25.16.172.in-addr.arpa. (44)
        0x0000:  0014 5e67 261d 0001 6c99 1468 0800 4500  ..^g&...l..h..E.
        0x0010:  0048 5a83 4000 4011 5e25 ac10 197e ac10  .HZ.@.@.^%...~..
        0x0020:  105e ee18 0035 0034 8242 391c 0100 0001  .^...5.4.B9.....
        0x0030:  0000 0000 0000 0331 3235 0232 3502 3136  .......125.25.16
        0x0040:  0331 3732 0769 6e2d 6164 6472 0461 7270  .172.in-addr.arp
        0x0050:  6100 000c 0001                           a.....

6. Capture and Save Packets in a File

As we said, that tcpdump has a feature to capture and save the file in a .pcap format, to do this just execute command with -w option.

# tcpdump -w 0001.pcap -i eth0

tcpdump: listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
4 packets captured
4 packets received by filter
0 packets dropped by kernel

7. Read Captured Packets File

To read and analyze captured packet 0001.pcap file use the command with -r option, as shown below.

# tcpdump -r 0001.pcap

reading from file 0001.pcap, link-type EN10MB (Ethernet)
09:59:34.839117 IP 192.168.0.2.ssh > 192.168.0.1.nokia-ann-ch1: Flags [P.], seq 3353041614:3353041746, ack 4193563273, win 18760, length 132
09:59:34.963022 IP 192.168.0.1.nokia-ann-ch1 > 192.168.0.2.ssh: Flags [.], ack 132, win 65351, length 0
09:59:36.935309 IP 192.168.0.1.netbios-dgm > 192.168.0.255.netbios-dgm: NBT UDP PACKET(138)
09:59:37.528731 IP 192.168.0.1.nokia-ann-ch1 > 192.168.0.2.ssh: Flags [P.], seq 1:53, ack 132, win 65351, length 5

8. Capture IP address Packets

To capture packets for a specific interface, run the following command with option -n.

# tcpdump -n -i eth0

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
12:07:03.952358 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 3509512873:3509513069, ack 3652639034, win 18760, length 196
12:07:03.952602 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 196, win 64171, length 0
12:07:03.953311 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 196:504, ack 1, win 18760, length 308
12:07:03.954288 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 504:668, ack 1, win 18760, length 164
12:07:03.954502 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 668, win 65535, length 0
12:07:03.955298 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 668:944, ack 1, win 18760, length 276
12:07:03.955425 IP 172.16.23.16.netbios-ns > 172.16.31.255.netbios-ns: NBT UDP PACKET(137): REGISTRATION; REQUEST; BROADCAST
12:07:03.956299 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 944:1236, ack 1, win 18760, length 292
12:07:03.956535 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 1236, win 64967, length 0

9. Capture only TCP Packets.

To capture packets based on TCP port, run the following command with option tcp.

# tcpdump -i eth0 tcp

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
12:10:36.216358 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 3509646029:3509646225, ack 3652640142, win 18760, length 196
12:10:36.216592 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 196, win 64687, length 0
12:10:36.219069 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 196:504, ack 1, win 18760, length 308
12:10:36.220039 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 504:668, ack 1, win 18760, length 164
12:10:36.220260 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 668, win 64215, length 0
12:10:36.222045 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 668:944, ack 1, win 18760, length 276
12:10:36.223036 IP 172.16.25.126.ssh > 172.16.25.125.apwi-rxspooler: Flags [P.], seq 944:1108, ack 1, win 18760, length 164
12:10:36.223252 IP 172.16.25.125.apwi-rxspooler > 172.16.25.126.ssh: Flags [.], ack 1108, win 65535, length 0
^C12:10:36.223461 IP mid-pay.midcorp.mid-day.com.netbios-ssn > 172.16.22.183.recipe: Flags [.], seq 283256512:283256513, ack 550465221, win 65531, length 1[|SMB]

10. Capture Packet from Specific Port

Let’s say you want to capture packets for specific port 22, execute the below command by specifying port number 22 as shown below.

# tcpdump -i eth0 port 22

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
10:37:49.056927 IP 192.168.0.2.ssh > 192.168.0.1.nokia-ann-ch1: Flags [P.], seq 3364204694:3364204890, ack 4193655445, win 20904, length 196
10:37:49.196436 IP 192.168.0.2.ssh > 192.168.0.1.nokia-ann-ch1: Flags [P.], seq 4294967244:196, ack 1, win 20904, length 248
10:37:49.196615 IP 192.168.0.1.nokia-ann-ch1 > 192.168.0.2.ssh: Flags [.], ack 196, win 64491, length 0
10:37:49.379298 IP 192.168.0.2.ssh > 192.168.0.1.nokia-ann-ch1: Flags [P.], seq 196:616, ack 1, win 20904, length 420
10:37:49.381080 IP 192.168.0.2.ssh > 192.168.0.1.nokia-ann-ch1: Flags [P.], seq 616:780, ack 1, win 20904, length 164
10:37:49.381322 IP 192.168.0.1.nokia-ann-ch1 > 192.168.0.2.ssh: Flags [.], ack 780, win 65535, length 0

11. Capture Packets from source IP

To capture packets from source IP, say you want to capture packets for 192.168.0.2, use the command as follows.

# tcpdump -i eth0 src 192.168.0.2

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
10:49:15.746474 IP 192.168.0.2.ssh > 192.168.0.1.nokia-ann-ch1: Flags [P.], seq 3364578842:3364579038, ack 4193668445, win 20904, length 196
10:49:15.748554 IP 192.168.0.2.56200 > b.resolvers.Level3.net.domain: 11289+ PTR? 1.0.168.192.in-addr.arpa. (42)
10:49:15.912165 IP 192.168.0.2.56234 > b.resolvers.Level3.net.domain: 53106+ PTR? 2.0.168.192.in-addr.arpa. (42)
10:49:16.074720 IP 192.168.0.2.33961 > b.resolvers.Level3.net.domain: 38447+ PTR? 2.2.2.4.in-addr.arpa. (38)

12. Capture Packets from destination IP

To capture packets from destination IP, say you want to capture packets for 50.116.66.139, use the command as follows.

# tcpdump -i eth0 dst 50.116.66.139

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
10:55:01.798591 IP 192.168.0.2.59896 > 50.116.66.139.http: Flags [.], ack 2480401451, win 318, options [nop,nop,TS val 7955710 ecr 804759402], length 0
10:55:05.527476 IP 192.168.0.2.59894 > 50.116.66.139.http: Flags [F.], seq 2521556029, ack 2164168606, win 245, options [nop,nop,TS val 7959439 ecr 804759284], length 0
10:55:05.626027 IP 192.168.0.2.59894 > 50.116.66.139.http: Flags [.], ack 2, win 245, options [nop,nop,TS val 7959537 ecr 804759787], length 0

This article may help you to explore tcpdump command in depth and also to capture and analysis packets in future. There are number of options available, you can use the options as per your requirement. Please share if you find this article useful through our comment box.

Source

psacct or acct both are open source application for monitoring users activities on the system. These applications runs in the background and keeps track of each users activity on your system as well as what resources are being consumed.

I personally used this program in our company, we have development team where our developers continuously work on servers. So, this is one of best program to keep a eye on them. This program provides an excellent way to monitor what users are doing, what commands are they firing, how much resources are being consumed by them, how long users are active on the system. Another great feature of this program is it gives total resources consumed by services like Apache, MySQL, FTP,SSH etc.

Read Also: Monitor Linux Commands Executed by System Users in Real-time

I think this is one of the great and must needed application for every Linux/Unix System Administrators, who wanted to keep a track of user activities on their servers/systems.

The psacct or acct package provides several features for monitoring process activities.

1. ac command prints the statistics of user logins/logouts (connect time) in hours.
2. lastcomm command prints the information of previously executed commands of user.
3. accton commands is used to turn on/off process for accounting.
4. sa command summarizes information of previously executed commands.
5. last and lastb commands show listing of last logged in users.

Installing psacct or acct Packages

psacct or acct both are similar packages and there is not much difference between them, but the psacctpackage only available for rpm based distributions such as RHEL, CentOS and Fedora, whereas acct package available for distributions like Ubuntu, Debian and Linux Mint.

To install psacct package under rpm based distributions issue the following yum command.

# yum install psacct

To install acct package using apt-get command under Ubuntu / Debian / Linux Mint.

$ sudo apt-get install acct

OR

# apt-get install acct

Starting psacct or acct service

By default psacct service is in disabled mode and you need to start it manually under RHEL/CentOS/Fedorasystems. Use the following command to check the status of service.

# /etc/init.d/psacct status
Process accounting is disabled.

You see the status showing as disabled, so let’s start it manually using the following both commands. These two commands will create a /var/account/pacct file and start services.

# chkconfig psacct on
# /etc/init.d/psacct start
Starting process accounting:                               [  OK  ]

After starting service, check the status again, you will get status as enabled as shown below.

# /etc/init.d/psacct status
Process accounting is enabled.

Under Ubuntu, Debian and Mint service is started automatically, you don’t need to start it again.

Display Statistics of Users Connect Time

ac command without specifying any argument will displays total statistics of connect time in hours based on the user logins/logouts from the current wtmp file.

# ac

total     1814.03

Display Statistics of Users Day-wise

Using command “ac -d” will prints out the total login time in hours by day-wise.

# ac -d

Sep 17  total        5.23
Sep 18  total       15.20
Sep 24  total        3.21
Sep 25  total        2.27
Sep 26  total        2.64
Sep 27  total        6.19
Oct  1  total        6.41
Oct  3  total        2.42
Oct  4  total        2.52
Oct  5  total        6.11
Oct  8  total       12.98
Oct  9  total       22.65
Oct 11  total       16.18

Display Time Totals for each User

Using command “ac -p” will print the total login time of each user in hours.

# ac -p

        root                              1645.18
        tecmint                            168.96
        total     1814.14

Display Individual User Time

To get the total login statistics time of user “tecmint” in hours, use the command as.

# ac tecmint

 total      168.96

Display Day-Wise Logn Time of User

The following command will prints the day-wise total login time of user “tecmint” in hours.

# ac -d tecmint

Oct 11  total        8.01
Oct 12  total       24.00
Oct 15  total       70.50
Oct 16  total       23.57
Oct 17  total       24.00
Oct 18  total       18.70
Nov 20  total        0.18

Print All Account Activity Information

The “sa” command is used to print the summary of commands that were executed by users.

# sa

       2       9.86re       0.00cp     2466k   sshd*
       8       1.05re       0.00cp     1064k   man
       2      10.08re       0.00cp     2562k   sshd
      12       0.00re       0.00cp     1298k   psacct
       2       0.00re       0.00cp     1575k   troff
      14       0.00re       0.00cp      503k   ac
      10       0.00re       0.00cp     1264k   psacct*
      10       0.00re       0.00cp      466k   consoletype
       9       0.00re       0.00cp      509k   sa
       8       0.02re       0.00cp      769k   udisks-helper-a
       6       0.00re       0.00cp     1057k   touch
       6       0.00re       0.00cp      592k   gzip
       6       0.00re       0.00cp      465k   accton
       4       1.05re       0.00cp     1264k   sh*
       4       0.00re       0.00cp     1264k   nroff*
       2       1.05re       0.00cp     1264k   sh
       2       1.05re       0.00cp     1120k   less
       2       0.00re       0.00cp     1346k   groff
       2       0.00re       0.00cp     1383k   grotty
       2       0.00re       0.00cp     1053k   mktemp
       2       0.00re       0.00cp     1030k   iconv
       2       0.00re       0.00cp     1023k   rm
       2       0.00re       0.00cp     1020k   cat
       2       0.00re       0.00cp     1018k   locale
       2       0.00re       0.00cp      802k   gtbl

Where

1. 9.86re is a “real time” as per wall clock minutes
2. 0.01cp is a sum of system/user time in cpu minutes
3. 2466k is a cpu-time averaged core usage, i.e. 1k units
4. sshd command name

Print Individual User Information

To get the information of individual user, use the options -u.

# sa -u

root       0.00 cpu      465k mem accton
root       0.00 cpu     1057k mem touch
root       0.00 cpu     1298k mem psacct
root       0.00 cpu      466k mem consoletype
root       0.00 cpu     1264k mem psacct           *
root       0.00 cpu     1298k mem psacct
root       0.00 cpu      466k mem consoletype
root       0.00 cpu     1264k mem psacct           *
root       0.00 cpu     1298k mem psacct
root       0.00 cpu      466k mem consoletype
root       0.00 cpu     1264k mem psacct           *
root       0.00 cpu      465k mem accton
root       0.00 cpu     1057k mem touch

Print Number of Processes

This command prints the total number of processes and CPU minutes. If you see continue increase in these numbers, then its time to look into the system about what is happening.

# sa -m

sshd                                    2       9.86re       0.00cp     2466k
root                                  127      14.29re       0.00cp      909k

Print Sort by Percentage

The command “sa -c” displays the highest percentage of users.

# sa -c

 132  100.00%      24.16re  100.00%       0.01cp  100.00%      923k
       2    1.52%       9.86re   40.83%       0.00cp   53.33%     2466k   sshd*
       8    6.06%       1.05re    4.34%       0.00cp   20.00%     1064k   man
       2    1.52%      10.08re   41.73%       0.00cp   13.33%     2562k   sshd
      12    9.09%       0.00re    0.01%       0.00cp    6.67%     1298k   psacct
       2    1.52%       0.00re    0.00%       0.00cp    6.67%     1575k   troff
      18   13.64%       0.00re    0.00%       0.00cp    0.00%      509k   sa
      14   10.61%       0.00re    0.00%       0.00cp    0.00%      503k   ac
      10    7.58%       0.00re    0.00%       0.00cp    0.00%     1264k   psacct*
      10    7.58%       0.00re    0.00%       0.00cp    0.00%      466k   consoletype
       8    6.06%       0.02re    0.07%       0.00cp    0.00%      769k   udisks-helper-a
       6    4.55%       0.00re    0.00%       0.00cp    0.00%     1057k   touch
       6    4.55%       0.00re    0.00%       0.00cp    0.00%      592k   gzip
       6    4.55%       0.00re    0.00%       0.00cp    0.00%      465k   accton
       4    3.03%       1.05re    4.34%       0.00cp    0.00%     1264k   sh*
       4    3.03%       0.00re    0.00%       0.00cp    0.00%     1264k   nroff*
       2    1.52%       1.05re    4.34%       0.00cp    0.00%     1264k   sh
       2    1.52%       1.05re    4.34%       0.00cp    0.00%     1120k   less
       2    1.52%       0.00re    0.00%       0.00cp    0.00%     1346k   groff
       2    1.52%       0.00re    0.00%       0.00cp    0.00%     1383k   grotty
       2    1.52%       0.00re    0.00%       0.00cp    0.00%     1053k   mktemp

List Last Executed Commands of User

The ‘latcomm‘ command is used to search and display previously executed user commands information. You can also search commands of individual usernames. For example, we see commands of user (tecmint).

# lastcomm tecmint

su                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56
ls                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56
ls                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56
ls                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56
bash               F    tecmint  pts/0      0.00 secs Wed Feb 13 15:56
id                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56
grep                    tecmint  pts/0      0.00 secs Wed Feb 13 15:56
grep                    tecmint  pts/0      0.00 secs Wed Feb 13 15:56
bash               F    tecmint  pts/0      0.00 secs Wed Feb 13 15:56
dircolors               tecmint  pts/0      0.00 secs Wed Feb 13 15:56
bash               F    tecmint  pts/0      0.00 secs Wed Feb 13 15:56
tput                    tecmint  pts/0      0.00 secs Wed Feb 13 15:56
tty                     tecmint  pts/0      0.00 secs Wed Feb 13 15:56
bash               F    tecmint  pts/0      0.00 secs Wed Feb 13 15:56
id                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56
bash               F    tecmint  pts/0      0.00 secs Wed Feb 13 15:56
id                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56

Search Logs for Commands

With the help of the lastcomm command you will be able to view individual use of an each commands.

# lastcomm ls

ls                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56
ls                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56
ls                      tecmint  pts/0      0.00 secs Wed Feb 13 15:56

Source

Scrot (SCReenshOT) is an open source, powerful and flexible, command line utility for taking screen shots of your Desktop, Terminal or a Specific Window manually or automatically by Cron job. Scrot is similar to Linux ‘import‘ command, but uses ‘imlib2‘ library to capture and save images. It supports multiple image formats (JPG, PNG, GIF, etc), which you can specify while taking screen shots by using the tool.

Features of Scrot

1. With scrot we can take screen shots easily without any additional work.
2. We can also optimize the quality of the screen shots image (with the -q switch, followed by a quality level between 1 and 100. The default quality level is 75.
3. It is very easy to installation and use.
4. We can capture a specific window or a rectangular area on the screen with the help of switch.
5. Can get all screen shots in a particular directory and also can store all screen shots in a remote PC or network server.
6. Can monitor all Desktop PC in admin absent and prevent to unwanted activities.

Installing Scrot in Linux

We can install ‘Scrot‘ on any Linux distribution. If you’re using RedHat or Debian based distribution, you can use a package manager tool like yum or apt-get to install it as shown below.

# yum install scrot			[On RedHat based Systems]

$ sudo apt-get install scrot		[On Debian based Systems]

If you wish to install it from source code, then use the following commands.

$ wget http://linuxbrit.co.uk/downloads/scrot-0.8.tar.gz
$ tar -xvf scrot-0.8.tar.gz
$ cd /scrot-0.8
$ ./configure
$ make
$ su -c "make install"

Note: RedHat users, need to specify prefix location with configure command.

$ ./configure --prefix=/usr

How to Use Scrot to take Screen shots

As I said above, scrot can capture an entire desktop, a terminal or a specific window. With the help of scrot you can also take screen shots of a shell/terminal of a system that doesn’t have a GUI support.

Take Full Desktop Screen Shot

Let’s take a entire screen shot of the Desktop, using the following command in your terminal.

$ scrot /home/tecmint/Desktop.jpg

Take Specific Window Screen Shot

If you would like to capture a specific area on the screen, you can use the following command with ‘-s’ switch that allows you to interactively select the area with your mouse that you wish to take screen shot.

scrot -s /home/tecmint/Window.jpg

Adjusting the Image Quality

With the help of ‘-q‘ switch, you can specify the quality level of the image between 1 and 100. The default image level is set to 75, and the image output will be different depending upon the file format you specify.

The following command will capture an image at 90% the quality of the original high quality screen.

$ scrot -q 90 /home/tecmint/Quality.jpg

Take Screen Shots Automatically

Now if you would like to get automatically screen shots, than you need to create a simple shell script. Create a file ‘screen.sh‘ with ‘touch‘ command and add the following content to it.

#!/bin/sh
DISPLAY=:0 scrot 'tecmint-%Y-%m-%d-%H_%M.jpg' -q 20 && mv /home/tecmint/*.jpg /media/tecmint

Now grant ‘777‘ permission and set an Cron job.

$ chmod 777 screen.sh

Open a ‘crontab‘ file and add the following entry. You can define custom interval time.

$ crontab -e

*/1 * * * * sh /home/tecmint/screen.sh

The above Cron entry will run every ‘1‘ minute and take screen shots and store them under ‘/media/tecmint‘ directory with filename as date and time. After running script for 1 minute, this is what I found in my ‘tecmint’directory.

Reference Links

http://linuxbrit.co.uk/software/

Source

FireSSH is an open source cross platform browser based SSH terminal client extension for Firefox, developed by Mime Čuvalo using JavaScript for handling accessible and reliable remote SSH sessions right from the browser window and acts as a much powerful SSH client.

This small lightweight add-on enables you to easily create new accounts and make new connections to the systems. You don’t need to install third party tools like Putty or other SSH client on your machine, all you need is to have a web browser in your place to access your remote machines from the browser wherever you go or on the go.

Installation of FireSSH

Firstly, you must have a Firefox browser installed on your system. FireSSH is not a standalone program, but created as an extension to Firefox browser. To install FireSSH, go to the following link and click on the “Install Now” button, Once it finishes installation, make sure you restarted Firefox successfully,

1. https://addons.mozilla.org/firefox/downloads/latest/firessh

How to Start FireSSH?

FireSSH extension uses SSH protocol to connect to remote host. For example if you would like to connect to host “172.16.25.126” using the user “tecmint” and password “xyz” you would type in the address bar similar to “ssh://172.16.25.126” and enter details as suggested.

Askbot is an open source, simple yet powerful, fast and highly-customizable software for creating a question and answer (Q&A) forum. It is inspired by StackOverflow and YahooAnswers, and written in Python on top of the Django web framework.

It allows for efficient question and answer knowledge management, thus organizations such as Fedora’s Q&A forums and LibreOffice’s Q&A Forums are making good use of it. Askbot can work as a standalone application or can be integrated with your existing Django apps or other web platforms.

In this tutorial you will learn how to install AskBot on CentOS 7. In order to complete the tutorial, you will need to have a CentOS 7 server minimal installation with root access.

Step 1: Install Required Dependencies

We will start by installing the required dependencies such as development tools by using the following command in a terminal.

# yum group install 'Development Tools'

After that we will install Epel repository, if it hasn’t already been installed on your system.

# yum install epel-release

Lastly, we will install some of the python dependencies required to later run AskBot.

# yum install python-pip python-devel python-six

In case python-pip is not installed with the above command, you can install it with by using the following command.

# curl "https://bootstrap.pypa.io/get-pip.py" -o "get-pip.py" && python get-pip.py

Step 2: Install PostgreSQL Database

AskBot requires a database where it will store its data. It uses PostgreSQL, so we will need to install it and configure it on our system.

You can use the following command to complete the installation.

# yum -y install postgresql-server postgresql-devel postgresql-contrib

When the installation is complete, initialize PostgreSQL with.

# postgresql-setup initdb

If everything goes normally, you should see the following:

Initializing database ... OK

Our next step is to start PostgreSQL and enable it to start on boot:

# systemctl start postgresql
# systemctl enable postgresql

Now that our database server is up and running, we will login as postgres user to create a database for our AskBot installation.

# su - postgres

Then use to:

$ psql

Now you are the PostgreSQL prompt, ready to create our database, database user and grant the user privileges on the new database. Create the database by using the command below, feel free to change the database name per your preferences:

postgres=# create database askbot_db;

Next create the database user. Replace “password_here” with a strong password:

postgres=# create user askbot_user with password 'password_here';

Grant the user privileges on the askbot_db:

postgres=# grant all privileges on database askbot_db to askbot_user;

Next we will need to edit the PostgreSQL configuration to change our authentication method to md5. To do this, use your favorite text editor and edit /var/lib/pgsql/data/pg_hba.conf file:

# vim /var/lib/pgsql/data/pg_hba.conf

The configurations should look like this:

Next save the changes and restart PostgreSQL:

# systemctl restart postgresql

Step 3: Install AskBot Forum

Finally we can proceed with the installation of AskBot. Start by creating new user on your system. We will call it askbot:

# useradd -m -s /bin/bash askbot

Setup password for the new user:

# passwd askbot

Next we will need to add the user to the wheel group on the system:

# usermod -a -G wheel askbot

Now we will use pip to install virtualenv package:

# pip install virtualenv six

Now we will log as the askbot user and create new virtual environment:

# su - askbot
$ virtualenv tecmint/

Sample Output

New python executable in /home/askbot/tecmint/python
Installing setuptools, pip, wheel...
done.

Next step is to activate the virtual environment with the following command:

# source tecmint/bin/activate

Now we are ready to install AskBot via pip.

# pip install six askbot psycopg2

The installation may take a couple of minutes. Once it is complete, we can test our installation in a temporary directory. Make sure NOT to name that directory askbot.

# mkdir forum_test && cd forum_test

Next we will initialize a new AskBot project with:

# askbot-setup

You will be asked a few question where you will have to select the installation directory – use “.” (without quotes) to choose the current directory. Next you will need to enter the earlier prepared database name, database user and its password.

Next we will generate the static files for Django with:

# python manage.py collectstatic

Next we generate the database:

# python manage.py syncdb

And finally start the server with:

# python manage.py runserver 127.0.0.1:8080

When you go to your browser to http://127.0.0.1:8080 – you should see the askbot interface.

That’s all! Askbot is an open source, simple, fast and highly-customizable question and answer (Q&A) forum software. It supports efficient question and answer knowledge management. If you encountered any errors during the installation or have any other related queries, use the feedback form below to reach us.

Source

Piwigo is an open source project which allows you to create your own photo gallery on the web and upload photos and create new albums. The platform includes some powerful features built-in, such as albums, tags, watermark, geolocation, calendars, system notifications, access control levels, themes and statistics.

Piwigo has a huge amount of available plugins (over 200) and a great collection of themes. It is also translated in more than 50 languages. Its core functions are written in PHP programming language and requires a RDBMS database backend, such as MySQL database.

This fact makes it easy to deploy Piwigo on top of a LAMP (Linux, Apache, MySQL and PHP) stack installed on your own server, VPS or on shared hosted environments.

An online demo is available for you to try before installing Piwigo on CentOS system.

Demo URL: http://piwigo.org/demo/

Requirements:

1. A dedicated VPS with a registered domain name
2. A CentOS 7 Server with Minimal Install
3. LAMP stack installed in CentOS 7

Piwigo is an open source project which can be deployed on a VPS server of your choice.

In this guide we’ll learn how to install and configure Piwigo image gallery software on top of a LAMP stack in a CentOS 7 VPS server.

Setting Up Pre-requirements for Piwigo

1. After you’ve installed LAMP stack on your VPS by following the guide in the article description, make sure you also install the below PHP extensions required by Piwigo to properly run on your server.

# yum install php php-xml php-mbstring php-gd

2. Next, install the following command line utilities on your VPS server in order to download and extract Piwigoarchive sources in your system.

# yum install unzip zip wget 

3. Next, log in to MySQL database and execute the below command in order to create Piwigo database and the user which will be used to manage the database. Replace the database name and credentials used in this tutorial with your own settings.

# mysql -u root -p
MariaDB [(none)]> create database piwigo;
MariaDB [(none)]>grant all privileges on piwigo.* to 'piwigouser'@'localhost' identified by 'pass123';
MariaDB [(none)]>flush privileges;
MariaDB [(none)]>exit

4. Next, open end edit PHP configuration file and set the correct timezone settings for your server. Use PHP docs to get the timezone settings list.

# nano /etc/php.ini

Locate and Insert the below line after [Date] statement.

date.timezone = Europe/Your_city

Save and close the file and restart Apache HTTP server to apply all changes, by issuing the below command.

# systemctl restart httpd

5. Next, completely disable SELinux in your CentOS system by executing the below commands. Use cat command to show Selinux configuration file.

# cat /etc/selinux/config 
# sed -i.backup 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config 
# cat /etc/selinux/config 
# setenforce 0
# getenforce

Install Piwigo in CentOS 7

6. On the next step, visit Piwigo official download page and grab the latest installer zip sources on your system using wget utility by issuing the below command. After download completes, extract Piwigo zip archive in your current working directory.

# wget http://piwigo.org/download/dlcounter.php?code=latest -O piwigo.zip
# ls 
# unzip piwigo.zip 

7. After you’ve extracted the zip archive, copy Piwigo sources files into your domain webroot path by issuing the below command. Afterwards, grant Apache account full privileges to webroot files and list the content of your web server document root path.

# cp -rf piwigo/* /var/www/html/
# chown -R apache:apache /var/www/html/
# ls -l /var/www/html/

8. Next, change the webroot file permissions for Piwigo installed files and grant _data directory full write permissions for other system users, by issuing the below commands.

# chmod -R 755 /var/www/html/
# chmod -R 777 /var/www/html/_data/
# ls -al /var/www/html/

9. Now, start the installation process of Piwigo. Open a browser and navigate to your server IP address or domain name.

http://192.168.1.164
OR
http://your-domain.com

On the first installation screen, select Piwigo language and insert MySQL database settings: host, user, password and table prefix. Also, add a Piwigo admin account with a strong password and the email address of the admin account. Finally, hit on Start installation button to install Piwigo.

10. After the installation has been completed, hit on Visit the gallery button in order to be redirected to Piwigo admin panel.

11. On the next screen, because no image has been uploaded to the server yet, hit on Start the Tour button in order to display the software guidance window and review all step required to upload your photos and use Piwigo image gallery.

That’s all! Now you can start creating image galleries and upload your image files to the server using one of the most flexible open source solutions to host your photos.

Fixing a broken Linux System can be a cumbersome job if you don’t have the idea of what exactly is going on. What most of us do when we gets a broken Linux system? Most of us searches the forum and/or google about the problem. While we hate troubles, how about installing a ‘Trouble Maker‘ application, which essentially creates troubles, gives you hard time and want you to fix broken system.

This is a nice way of learning to fix a broken Linux System. For this purpose, there is a special Linux Distroavailable called ‘Damn Vulnerable Linux’ (DVL), it’s bundled with ill-configured, outdated and exploitable tools which trains administrators to industry standard.

However, no any distribution or tool is a replacement for clearly understanding the Linux and experience in dealing with unknown problems. This is where, Trouble-Maker comes into the picture. With this “Trouble Maker” you can train Yourself on any standard Linux distribution and hence no specific distro is required.

In fact, you will never underestimate DVL distribution. The DVL distro contains a lot of broken applications and bugs whereas “Trouble Maker”, will provide you with 16 different modules.

Trouble Maker Components

Trouble Maker consists of three main components and they are:

1. The trouble-engine is developed in a cross platform way, so it can run on as many target platforms as feasible .
2. The trouble-modules are developed so as to denote which machines they apply to, and what requirements they have.
3. The trouble-module-builder is an extra module (optional) system designed to clarify packaging trouble-module files into certain modules. Currently not implemented.

At this time, only RedHat Enterprise Linux, CentOS, Fedora and SUSE Linux Enterprise Server are supported. When you install and run the “Trouble Maker” first time, it will randomly choose a problem from its set of modules and ask you to deal with boot problem, configuration problem, hardware problem and user reporting problem.

It is Strongly recommended not to install “Trouble Maker” on your Primary/Production Machine. Better use it on any of the ‘virtual machine‘ in order to remain away from any trouble or data loss.

Installation of Trouble-Maker in Linux

The application is a cross­-platform project and hence don’t come bundled with OS specific files/application. The project is developed in Perl programming language. Of course you need Perl installed on your Linux server, before using the application.

To install required Perl modules, you need to install and enable third party RPMForge repository under your systems. Please use the following article to enable repository.

Install and Enable RPMForge Repository in RHEL/CentOS

Once you’ve enabled RPMForge repository, you can run the following command to install required Perl modules.

# yum install perl-Archive-Tar perl-YAML

Now, download the latest Trouble-Maker application using the following download link or you may use the wget command to download it as shown.

http://sourceforge.net/projects/trouble­maker/files/

# cd /tmp
# wget http://kaz.dl.sourceforge.net/project/trouble-maker/trouble-maker/0.11/trouble-maker-0.11.tgz
# cd /
# tar -zxvf /tmp/trouble-maker-0.11.tgz
# /usr/local/trouble-maker/bin/trouble-maker.pl --version=RHEL_6

How to Run Trouble-Maker in Linux

The default mode for running trouble-maker is very easy to use. Simply run the following command with the version flag. For example, on RedHat Enterprise Linux 6, run the command as shown.

# /usr/local/trouble-maker/bin/trouble-maker.pl --version=RHEL_6

To run a specified module.

# /usr/local/trouble­maker/bin/trouble­maker.pl –version=RHEL_6 –selection=module_name

Trouble-Maker Problem Modules

Having a look at some of the System breaks, arising as a result of running Trouble Maker.

1. No GUI! Only command Line

Area to see: Your Runlevel has been modified from 5 to 3 in /etc/inittab file.

2. User ‘gdm’ don’t exist

Area to see: Modification in /etc/passwd file.

3. INIT: No more process in the runlevel

Area to see: Problem with /etc/inittab file.

4. Switchroot: Mount Failed: No such file or directory

Area to see: Location of root partition is modified. You need to change /boot/grub/grub.conf

5. Can’t log in as root

Area to see: You need to check file /etc/pam.d/login file.

6. initrd file not found

Area to see: correct /boot/grub/grub.conf

7. Network is not working

Area to see: You have to see at number of places. Check if ‘ifconfig’ command is working or not followed by looking into the file /etc/sysconfig/network file.

8. Log in to root denied, in console

Area to see: check /etc/pam.d/login file and /etc/security file and correct either or both of them.

9. FTP is not working

Area to see: check for errors in the ftp configuration file, /etc/hosts.allow and /etc/hosts.deny.

10. SSH not working

Area to see: Fix SSH configuration file.

Conclusion

I already describe 10 modules above, out of 16 modules of trouble maker, and leaving remaining 6 modules for you to explore. To be true 1 module is dummy hence you are left with 5 modules to explore and a total of 15 modules and 1 dummy module available in ‘Trouble Maker’. Run the program at your own risk. We are not responsible for any damage to your System/Server.

Reference Links

1. Product’s Homepage
2. Product’s Documentation

Hope you people would love the writing and tell us about your experience with ‘Trouble Maker’. That’s all for now and don’t forget to provide us with your valuable feedback in the comment section.

Source

Neoftech is a cross-platform and easy-to-use system information command line script that collects your Linux system information and display it on the terminal next to an image, it could be your distributions logo or any ascii art of your choice.

Recently, a new major version of Neofetch 3.0 released with large amount of breaking changes added to this update.

Neoftech is very similar to ScreenFetch or Linux_Logo utilities, but highly customizable and comes with some extra features as discussed below.

Its main features include: it’s fast, prints a full color image – your distributions logo in ASCII alongside your system information, it’s highly customizable in terms of which, where and when information is printed on the terminal and it can take a screenshot of your desktop when closing the script as enabled by a special flag.

Required Dependencies:

1. Bash 3.0+ with ncurses support.
2. w3m-img (occasionally packaged with w3m) or iTerm2 or Terminology for printing images.
3. imagemagick – for thumbnail creation.
4. Linux terminal emulator should support \033[14t [3] or xdotool or xwininfo + xprop or xwininfo + xdpyinfo .
5. On Linux, you need feh, nitrogen or gsettings for wallpaper support.

Important: You can read more about optional dependencies from the Neofetch Github repository to check if your Linux terminal emulator actually supports \033[14t or any extra dependencies for the script to work well on your distro.

How To Install Neofetch in Linux

Neofetch can be easily installed from third-party repositories on almost all Linux distributions by following below respective installation instructions as per your distribution.

On Debian

$ echo "deb http://dl.bintray.com/dawidd6/neofetch jessie main" | sudo tee -a /etc/apt/sources.list
$ curl -L "https://bintray.com/user/downloadSubjectPublicKey?username=bintray" -o Release-neofetch.key && sudo apt-key add Release-neofetch.key && rm Release-neofetch.key
$ sudo apt-get update
$ sudo apt-get install neofetch

On Ubuntu and Linux Mint

$ sudo add-apt-repository ppa:dawidd0811/neofetch
$ sudo apt-get update
$ sudo apt-get install neofetch

On RHEL, CentOS and Fedora

You need to have dnf-plugins-core installed on your system, or else install it with the command below:

$ sudo yum install dnf-plugins-core

Enable COPR repository and install neofetch package.

$ sudo dnf copr enable konimex/neofetch
$ sudo dnf install neofetch

On Arch Linux

You can either install neofetch or neofetch-git from the AUR using packer or Yaourt.

$ packer -S neofetch
$ packer -S neofetch-git
OR
$ yaourt -S neofetch
$ yaourt -S neofetch-git

On Gentoo

Install app-misc/neofetch from Gentoo/Funtoo’s official repositories. However, in case you need the git version of the package, you can install =app-misc/neofetch-9999.

How To Use Neofetch in Linux

Once you have installed the package, the general syntax for using it is:

$ neofetch

Note: If w3m-img or imagemagick is not installed on your system, screenfetch will be enabled by default and neofetch will display your ASCII art logo as in the image below.

Linux Mint Information

Ubuntu Information

If you want to display the default distribution logo as image, you should install w3m-img or imagemagick on your system as follows:

$ sudo apt-get install w3m-img    [On Debian/Ubuntu/Mint]
$ sudo yum install w3m-img        [On RHEL/CentOS/Fedora]

Then run neofetch again, you will see the default wallpaper of your Linux distributions as the image.

$ neofetch

After running neofetch for the first time, it will create a configuration file with all options and settings: $HOME/.config/neofetch/config.

This configuration file will enable you through the printinfo () function to alter the system information that you want to print on the terminal. You can type in new lines of information, modify the information lineup, delete certain lines and also tweak the script it using bash code to manage the information to be printed out.

You can open the configuration file using your favorite editor as follows:

$ vi ~/.config/neofetch/config

Below is an excerpt of the configuration file on my system showing the printinfo () function.

#!/usr/bin/env bash
# vim:fdm=marker
#
# Neofetch config file
# https://github.com/dylanaraps/neofetch

# Speed up script by not using unicode
export LC_ALL=C
export LANG=C

# Info Options {{{


# Info
# See this wiki page for more info:
# https://github.com/dylanaraps/neofetch/wiki/Customizing-Info
printinfo() {
    info title
    info underline

    info "Model" model
    info "OS" distro
    info "Kernel" kernel
    info "Uptime" uptime
    info "Packages" packages
    info "Shell" shell
    info "Resolution" resolution
    info "DE" de
    info "WM" wm
    info "WM Theme" wmtheme
    info "Theme" theme
    info "Icons" icons
    info "Terminal" term
    info "Terminal Font" termfont
    info "CPU" cpu
    info "GPU" gpu
    info "Memory" memory

    # info "CPU Usage" cpu_usage
    # info "Disk" disk
    # info "Battery" battery
    # info "Font" font
    # info "Song" song
    # info "Local IP" localip
    # info "Public IP" publicip
    # info "Users" users
    # info "Birthday" birthday

    info linebreak
    info cols
    info linebreak
}
.....

Type the command below to view all flags and their configuration values you can use with neofetch script:

$ neofetch --help

To launch neofetch with all functions and flags enabled, employ the --test flag:

$ neofetch --test

You can enable the ASCII art logo again using the --ascii flag:

$ neofetch --ascii

In this article, we have covered a simple and highly configuration/customizable command line script that gathers your system information and displays it on the terminal.

Remember to get in touch with us via the feedback form below to ask any questions or give us your thoughts concerning the neofetch script.

Last but not least, if you know of any similar scripts out there, do not hesitate to let us know, we will be pleased to hear from you.

Visit the neofetch Github repository.

Source

In this era of Information Technology, data is all important. A data needs to be available across several machines at one/different point of time. Thus the concept of cloud storage was introduced. ‘Dropbox‘, the file hosting and cloud storage service enables each of its user to create a special folder on each machine and then sync them so that on each box, the same folder with same content is available.

Here in this article we will be throwing light on Dropbox, its feature, usages, area of application and installation on various Linux distributions.

What is Dropbox?

Dropbox is a cloud storage service which provides real time data syncing across multiple platforms and architectures. It is a tool which is very useful in managing data on the go. It lets you edit, update content and share your work with your family and friends. Real time syncing across various devices is now a cake-walk.

Features of Dropbox

1. Get 2 GB online storage for free.
2. Get up-to 16 GB online storage with referrals.
3. Pro Dropbox account gets 500GB online storage.
4. Business accounts are supported and it starts with 1 TB online storage with 5 Users.
5. Available for all known platforms Windows, Mac and Linux.
6. Available for most of the mobile platforms Symbian, Android, iOS.
7. Available for most of the devices Laptops, Desktops, Servers, Mobile – Blackberry, iPhone, ipad.
8. Works even when you are working offline.
9. Transfer only changed/new content.
10. Can be configured to set bandwidth limit.
11. Files Available on the go.
12. Edit files in real-time directly in dropbox.
13. Easy sharing and User-Friendly file upload.

Installation of Dropbox in Linux

Firstly, go the official download page to grab a latest version (i.e. Dropbox 2.6.25) according to your system architecture.

1. https://www.dropbox.com/install?os=lnx

Alternatively, you may also use following direct links to download and install the latest version using following commands.

On Ubuntu/Linux Mint

$ wget https://linux.dropbox.com/packages/ubuntu/dropbox_1.6.0_i386.deb		[32-bit]
$ sudo dpkg -i dropbox_1.6.0_i386.deb

$ wget https://linux.dropbox.com/packages/ubuntu/dropbox_1.6.0_amd64.deb	[64-bit]
$ sudo dpkg -i dropbox_1.6.0_amd64.deb

On Debian

$ wget https://linux.dropbox.com/packages/debian/dropbox_1.6.0_i386.deb		[32-bit]
$ sudo dpkg -i dropbox_1.6.0_i386.deb

$ wget https://linux.dropbox.com/packages/debian/dropbox_1.6.0_amd64.deb	[64-bit]
$ sudo dpkg -i dropbox_1.6.0_amd64.deb

On RHEL/CentOS and Fedora

# wget https://linux.dropbox.com/packages/fedora/nautilus-dropbox-1.6.0-1.fedora.i386.rpm	[32-bit]
# rpm -Uvh nautilus-dropbox-1.6.0-1.fedora.i386.rpm

$ wget https://linux.dropbox.com/packages/fedora/nautilus-dropbox-1.6.0-1.fedora.x86_64.rpm	[64-bit]
# rpm -Uvh nautilus-dropbox-1.6.0-1.fedora.x86_64.rpm

After successful installation. Click ‘Start Dropbox‘ button to begin installation, it will download latest version for your system.

After that, Dropbox setup will prompt you to login with your existing account or create one if you don’t.

After this, we need to install Dropbox client across all the box we need. Just login and start syncing in real-time from the special Dropbox folder.

Security

Well security of data is a major concern and in cloud storage service, when you are not aware of where your data is going to be saved, can we trust Dropbox?

Well at present time, Dropbox don’t support own private key to secure data. But it stores data in encrypted form which means you can be assured that your data is safe.

It shows a promising future. No doubt the developer should concentrate more on security point of view.

Conclusion

Dropbox is a brilliant cloud storage Application, most of us are aware of. If you have not tried it till now, you must give it a try and mind it you would never regret.

Dropbox Homepage

That’s all for now.

Source