Year: 2019

In a previous article, we put together a list of 10 useful commands to collect system and hardware information in Linux. In this guide, we will narrow down to the CPU/processor, and show you various ways of extracting detailed information about your machine CPU.

Just to give you an overview, we will query information such as CPU architecture, vendor_id, model, model name, number of CPU cores, speed of each core and lots more.
Essentially, the /proc/cpuinfo contains this all info, every other command/utility gets its output from this file.

With that said, below are 9 commands for getting info about your Linux CPU.

1. Get CPU Info Using cat Command

You can simply view the information of your system CPU by viewing the contents of the /proc/cpuinfo file with the help of cat command as follows:

$ cat /proc/cpuinfo

processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 69
model name	: Intel(R) Core(TM) i5-4210U CPU @ 1.70GHz
stepping	: 1
microcode	: 0x1c
cpu MHz		: 1700.062
cache size	: 3072 KB
physical id	: 0
siblings	: 4
core id		: 0
cpu cores	: 2
apicid		: 0
initial apicid	: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm epb tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt dtherm ida arat pln pts
bugs		:
bogomips	: 4788.92
clflush size	: 64
cache_alignment	: 64
address sizes	: 39 bits physical, 48 bits virtual
power management:
......

To get a little specific, you can employ grep command – a CLI tool for searching plain-text data for lines matching a regular expression. This can help you only output vendor name, model name, number of processors, number of cores etc:

$ cat /proc/cpuinfo | grep 'vendor' | uniq		#view vendor name
$ cat /proc/cpuinfo | grep 'model name' | uniq		#display model name
$ cat /proc/cpuinfo | grep processor | wc -l		#count the number of processing units
$ cat /proc/cpuinfo | grep 'core id'			#show individual cores	

Suggested Read: How to Use ‘cat’ and ‘tac’ Commands with Examples in Linux

2. lscpu Command – Shows CPU Architecture Info

The command lscpu prints CPU architecture information from sysfs and /proc/cpuinfo as shown below:

$ lscpu

Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                4
On-line CPU(s) list:   0-3
Thread(s) per core:    2
Core(s) per socket:    2
Socket(s):             1
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 69
Model name:            Intel(R) Core(TM) i5-4210U CPU @ 1.70GHz
Stepping:              1
CPU MHz:               1303.687
CPU max MHz:           2700.0000
CPU min MHz:           800.0000
BogoMIPS:              4788.92
Virtualization:        VT-x
L1d cache:             32K
L1i cache:             32K
L2 cache:              256K
L3 cache:              3072K
NUMA node0 CPU(s):     0-3
Flags:                 fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm epb tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt dtherm ida arat pln pts

3. cpuid Command – Shows x86 CPU

The command cpuid dumps complete information about the CPU(s) collected from the CPUID instruction, and also discover the exact model of x86 CPU(s) from that information.

Make sure to install it before running it.

$ sudo apt install cpuid        #Debian/Ubuntu systems
$ sudo yum install cpuid	#RHEL/CentOS systems 
$ sudo dnf install cpuid	#Fedora 22+ 

Once installed, run cpuid to collect information concerning the x86 CPU.

$ cpuid

CPU 0:
   vendor_id = "GenuineIntel"
   version information (1/eax):
      processor type  = primary processor (0)
      family          = Intel Pentium Pro/II/III/Celeron/Core/Core 2/Atom, AMD Athlon/Duron, Cyrix M2, VIA C3 (6)
      model           = 0x5 (5)
      stepping id     = 0x1 (1)
      extended family = 0x0 (0)
      extended model  = 0x4 (4)
      (simple synth)  = Intel Mobile Core i3-4000Y / Mobile Core i5-4000Y / Mobile Core i7-4000Y / Mobile Pentium 3500U/3600U/3500Y / Mobile Celeron 2900U (Mobile U/Y) (Haswell), 22nm
   miscellaneous (1/ebx):
      process local APIC physical ID = 0x0 (0)
      cpu count                      = 0x10 (16)
      CLFLUSH line size              = 0x8 (8)
      brand index                    = 0x0 (0)
   brand id = 0x00 (0): unknown
   feature information (1/edx):
      x87 FPU on chip                        = true
      virtual-8086 mode enhancement          = true
      debugging extensions                   = true
      page size extensions                   = true
      time stamp counter                     = true
      RDMSR and WRMSR support                = true
      physical address extensions            = true
....

4. dmidecode Command – Shows Linux Hardware Info

dmidecode is a tool for retrieving hardware information of any Linux system. It dumps a computer’s DMI (a.k.a SMBIOS) table contents in a human-readable format for easy retrieval. The SMBIOS specification defines various DMI types, for CPU, use “processor” as follows:

$ sudo dmidecode --type processor

# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.

Handle 0x0004, DMI type 4, 42 bytes
Processor Information
	Socket Designation: U3E1
	Type: Central Processor
	Family: Core i5
	Manufacturer: Intel(R) Corporation
	ID: 51 06 04 00 FF FB EB BF
	Signature: Type 0, Family 6, Model 69, Stepping 1
	Flags:
		FPU (Floating-point unit on-chip)
		VME (Virtual mode extension)
		DE (Debugging extension)
		PSE (Page size extension)
		TSC (Time stamp counter)
		MSR (Model specific registers)
		PAE (Physical address extension)
		MCE (Machine check exception)
		CX8 (CMPXCHG8 instruction supported)
		APIC (On-chip APIC hardware supported)
		SEP (Fast system call)
		MTRR (Memory type range registers)
		PGE (Page global enable)
		MCA (Machine check architecture)
.....

5. Inxi Tool – Shows Linux System Information

Inxi is a powerful command line system information script intended for both console and IRC (Internet Relay Chat). You can use it to instantly retrieve hardware information.

You can install like so:

$ sudo apt install inxi 	#Debian/Ubuntu systems
$ sudo yum install inxi		#RHEL/CentOS systems 
$ sudo dnf install inxi		#Fedora 22+ 

To display complete CPU information, including per CPU clock-speed and CPU max speed (if available), use the -C flag as follows:

$ inxi -C

CPU:       Dual core Intel Core i5-4210U (-HT-MCP-) cache: 3072 KB 
           clock speeds: max: 2700 MHz 1: 1958 MHz 2: 1993 MHz 3: 1775 MHz 4: 1714 MHz

6. lshw Tool – List Hardware Configuration

lshw is a minimal tool for gathering in-depth information on the hardware configuration of a computer. You can use the -C option to select the hardware class, CPU in this case:

$ sudo lshw -C CPU

*-cpu                   
       description: CPU
       product: Intel(R) Core(TM) i5-4210U CPU @ 1.70GHz
       vendor: Intel Corp.
       physical id: 4
       bus info: cpu@0
       version: Intel(R) Core(TM) i5-4210U CPU @ 1.70GHz
       serial: To Be Filled By O.E.M.
       slot: U3E1
       size: 2626MHz
       capacity: 2700MHz
       width: 64 bits
       clock: 100MHz
       capabilities: x86-64 fpu fpu_exception wp vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid sse4_1 sse4_2 movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm epb tpr_shadow vnmi flexpriority ept vpid fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid xsaveopt dtherm ida arat pln pts cpufreq
       configuration: cores=2 enabledcores=2 threads=4

7. hardinfo – Shows Hardware Info in GTK+ Window

hardinfo displays hardware information in a GTK+ window, you can install it as follows:

$ sudo apt install hardinfo 	#Debian/Ubuntu systems
$ sudo yum install hardinfo	#RHEL/CentOS systems 
$ sudo dnf install hardinfo	#Fedora 22+ 

Once you have it installed, type:

$ hardinfo 

It also enables you to generate a system hardware info report by clicking on the “Generate Report” button. From the interface below, click on “Generate” to proceed. Note that you can choose the hardware info category to be generated.

Once you have generated the report in html format, you can view it from a web browser as shown below.

8. hwinfo – Shows Present Hardware Info

hwinfo is used to extract info about hardware present in a Linux system. To display info about your CPU, use the --cpu

$ hwinfo --cpu

01: None 00.0: 10103 CPU                                        
  [Created at cpu.460]
  Unique ID: rdCR.j8NaKXDZtZ6
  Hardware Class: cpu
  Arch: X86-64
  Vendor: "GenuineIntel"
  Model: 6.69.1 "Intel(R) Core(TM) i5-4210U CPU @ 1.70GHz"
  Features: fpu,vme,de,pse,tsc,msr,pae,mce,cx8,apic,sep,mtrr,pge,mca,cmov,pat,pse36,clflush,dts,acpi,mmx,fxsr,sse,sse2,ss,ht,tm,pbe,syscall,nx,pdpe1gb,rdtscp,lm,constant_tsc,arch_perfmon,pebs,bts,rep_good,nopl,xtopology,nonstop_tsc,aperfmperf,eagerfpu,pni,pclmulqdq,dtes64,monitor,ds_cpl,vmx,est,tm2,ssse3,sdbg,fma,cx16,xtpr,pdcm,pcid,sse4_1,sse4_2,movbe,popcnt,tsc_deadline_timer,aes,xsave,avx,f16c,rdrand,lahf_lm,abm,epb,tpr_shadow,vnmi,flexpriority,ept,vpid,fsgsbase,tsc_adjust,bmi1,avx2,smep,bmi2,erms,invpcid,xsaveopt,dtherm,ida,arat,pln,pts
  Clock: 2080 MHz
  BogoMips: 4788.92
  Cache: 3072 kb
  Units/Processor: 16
  Config Status: cfg=new, avail=yes, need=no, active=unknown
....

9. nproc – Print Number of Processing Units

nproc command is used to show the number of processing unit present on your computer:

$ nproc

For additional usage info and options, read through the man pages of these commands like this:

$ man commandname

Also check out:

1. 1. Cpustat – Monitors CPU Utilization by Running Processes in Linux
   2. CoreFreq – A Powerful CPU Monitoring Tool for Linux Systems
   3. Find Top Running Processes by Highest Memory and CPU Usage in Linux
   4. How to Impose High CPU Load and Stress Test on Linux Using ‘Stress-ng’ Tool

That’s it for now! You can share with us additional ways of extracting CPU information in Linux via the feedback form below.

Source

As promised in our earlier tutorials of Apache Series, Today we are here with another article on the Apache HTTP web server which can make a System Administrators life much easier to handle load of Apache web server using mod_status module.

What is mod_status?

mod_status is an Apache module which helps to monitor web server load and current httpd connections with an HTML interface which can be accessible via a web browser.

Apache’s mod_status shows a plain HTML page containing the information about current statistics of web server state including.

1. Total number of incoming requests
2. Total number of bytes and counts server
3. CPU usage of Web server
4. Server Load
5. Server Uptime
6. Total Traffic
7. Total number of idle workers
8. PIDs with respective client and many more.

The default Apache Project enabled their server statistics page to the general public. To have a demo of busy web site’s status page, visit.

1. http://www.apache.org/server-status

Testing Environment

We have used following Testing Environment for this article to explore more about mod_status with some practical examples and screen-shots.

1. Operating System – CentOS 6.5
2. Application – Apache Web Server
3. IP Address – 5.175.142.66
4. DocumentRoot– /var/www/html
5. Apache Configuration file – /etc/httpd/conf/httpd.conf (for Red Hat)
6. Default HTTP Port – 80 TCP
7. Test Configuration Settings – httpd -t

The prerequisites for this tutorial is that you should already aware how to install and configure a Basic Apache Server. If you don’t know how to setup Apache, read the following article that might help you in setting up your own Apache Web Server.

1. Create Your Own Webserver and Hosting A Website in Linux

How to Enable mod_status in Apache

The default Apache installation comes with mod_status enabled. If not, make sure to enable it in Apache configuration file at.

[root@tecmint ~]# vi /etc/httpd/conf/httpd.conf

Search for the word “mod_status” or keep scrolling down until you find a line containing.

#LoadModule status_module modules/mod_status.so

If you see a ‘#‘ character at the beginning of “LoadModule”, that means mod_status is disabled. Remove the ‘#‘ to enable mod_status.

LoadModule status_module modules/mod_status.so

Configure mod_status

Now again search for the word “Location” or scroll down until you find a section for mod_status which should look like following.

# Allow server status reports generated by mod_status,
# with the URL of http://servername/server-status
# Change the ".example.com" to match your domain to enable.
#
#<Location /server-status>
#    SetHandler server-status
#    Order deny,allow
#    Deny from all
#    Allow from .example.com
#</Location>

In the above section, uncomment the lines for Location directive, SetHandler and the directory restrictionsaccording to your needs. For example, I am keeping it simple with the Order Allow, deny and it’s allowed for all.

<Location /server-status>
   SetHandler server-status
   Order allow,deny
   Deny from all
   Allow from all 
</Location>

Note : The above configuration is the default configuration for default Apache web site (single website). If you’ve created one or more Apache Virtual Hosts, the above configuration will won’t work.

So, basically, you need to define the same configuration for each virtual host for any domains you’ve configured in Apache. For example, the virtual host configuration for mod_status will look like this.

<VirtualHost *:80>
    ServerAdmin tecmint@example.com
    DocumentRoot /var/www/html/example.com
    ServerName example.com
    ErrorLog logs/example.com-error_log
    CustomLog logs/example.com-access_log common
<Location /server-status>
   SetHandler server-status
   Order allow,deny
   Deny from all
   Allow from example.com 
</Location>
</VirtualHost>

Enable ExtendedStatus

The “ExtendedStatus” settings adds more information to the statistics page like, CPU usage, request per second, total traffic, etc. To enable it, edit the the same httpd.conf file and search for the word “Extended” and Uncomment the line and set the status “On” for ExtendedStatus directive.

# ExtendedStatus controls whether Apache will generate "full" status
# information (ExtendedStatus On) or just basic information (ExtendedStatus
# Off) when the "server-status" handler is called. The default is Off.
#
ExtendedStatus On

Restart Apache

Now make sure that you’ve correctly enabled and configured Apache server status page. You can also check for the errors in the httpd.conf configuration using following command.

[root@tecmint ~]# httpd -t

Syntax OK

Once, you get syntax is OK, you can able to restart the httpd service.

[root@tecmint ~]# service httpd restart
Stopping httpd:                                          [  OK  ]
Starting httpd:                                          [  OK  ]

Access mod_status Page

The Apache status page will be accessible via your domain name with “/server-status” at the following URL’s.

http://serveripaddress/server-status

OR

http://serev-hostname/server-status

You will see something similar to the following page with ExtendedStatus enabled.

In above Snapshot, you can see that an HTML interface, which shows all information about server uptime, process Id with its respective client, the page they are trying to access.

It also shows the meaning and usage of all the abbreviations used to display the status which helps us to understand the situation better.

You can also refresh the page every time seconds (say 5 seconds) to see the updated statistics. To set the automate refresh, please add “?refresh=N” at the end of the URL. Where N can be replaced with the number of seconds which you want your page to get refreshed.

http://serveripaddress/server-status/?refresh=5

Command line Status Page View

You can also view the Apache status page from the command-line interface using the special command-line browsers called links or lynx. You can install them using default package manager utility called yum as shown below.

# yum install links

OR

# yum install lynx

Once, you’ve installed the, you can get the same statistics on your terminal by using following command.

[root@tecmint ~]# links http://serveripaddress/server-status
OR
[root@tecmint ~]# lynx http://serveripaddress/server-status
OR
[root@tecmint ~]#  /etc/init.d/httpd fullstatus

Sample Output

                     Apache Server Status for localhost
   Server Version: Apache/2.2.15 (Unix) DAV/2 PHP/5.3.3
   Server Built: Aug 13 2013 17:29:28

   --------------------------------------------------------------------------
   Current Time: Tuesday, 14-Jan-2014 04:34:13 EST
   Restart Time: Tuesday, 14-Jan-2014 00:33:05 EST
   Parent Server Generation: 0
   Server uptime: 4 hours 1 minute 7 seconds
   Total accesses: 2748 - Total Traffic: 9.6 MB
   CPU Usage: u.9 s1.06 cu0 cs0 - .0135% CPU load
   .19 requests/sec - 695 B/second - 3658 B/request
   1 requests currently being processed, 4 idle workers
 .__.__W...

   Scoreboard Key:
   "_" Waiting for Connection, "S" Starting up, "R" Reading Request,
   "W" Sending Reply, "K" Keepalive (read), "D" DNS Lookup,
   "C" Closing connection, "L" Logging, "G" Gracefully finishing,
   "I" Idle cleanup of worker, "." Open slot with no current process

Srv PID     Acc    M CPU   SS  Req Conn Child Slot     Client        VHost             Request
0-0 -    0/0/428   . 0.30 5572 0   0.0  0.00  1.34 127.0.0.1      5.175.142.66 OPTIONS * HTTP/1.0
                                                                               GET
1-0 5606 0/639/639 _ 0.46 4    0   0.0  2.18  2.18 115.113.134.14 5.175.142.66 /server-status?refresh=5
                                                                               HTTP/1.1
                                                                               GET
2-0 5607 0/603/603 _ 0.43 0    0   0.0  2.09  2.09 115.113.134.14 5.175.142.66 /server-status?refresh=5
                                                                               HTTP/1.1
3-0 -    0/0/337   . 0.23 5573 0   0.0  0.00  1.09 127.0.0.1      5.175.142.66 OPTIONS * HTTP/1.0
                                                                               GET
4-0 5701 0/317/317 _ 0.23 9    0   0.0  1.21  1.21 115.113.134.14 5.175.142.66 /server-status?refresh=5
                                                                               HTTP/1.1
                                                                               GET
5-0 5708 0/212/213 _ 0.15 6    0   0.0  0.85  0.85 115.113.134.14 5.175.142.66 /server-status?refresh=5
                                                                               HTTP/1.1
6-0 5709 0/210/210 W 0.16 0    0   0.0  0.84  0.84 127.0.0.1      5.175.142.66 GET /server-status
                                                                               HTTP/1.1
7-0 -    0/0/1     . 0.00 5574 0   0.0  0.00  0.00 127.0.0.1      5.175.142.66 OPTIONS * HTTP/1.0

   --------------------------------------------------------------------------

    Srv  Child Server number - generation
    PID  OS process ID
    Acc  Number of accesses this connection / this child / this slot
     M   Mode of operation
    CPU  CPU usage, number of seconds
    SS   Seconds since beginning of most recent request
    Req  Milliseconds required to process most recent request
   Conn  Kilobytes transferred this connection
   Child Megabytes transferred this child
   Slot  Total megabytes transferred this slot
   --------------------------------------------------------------------------

    Apache/2.2.15 (CentOS) Server at localhost Port 80

Conclusion

Apache’s mod_status module is a very handy monitoring tool for monitoring performance of a web server’s activity and can able to highlight problems itself. For more information read the status page that can be help you to become a more successful web server administrator.

1. Apache mod_status Homepage

That’s all for mod_status for now.

Source

As promised in our previous two articles (Perform Internal Redirection with mod_rewrite and Show Custom Content Based on Browser), in this post we will explain how to perform a redirection to a resource that has been moved from one server to a different server in Apache using mod_rewrite module.

Suppose you are redesigning your company’s Intranet site. You have decided to store the content and styling (HTML files, JavaScript, and CSS) on one server and the documentation on another – perhaps a more robust one.

Suggested Read: 5 Tips to Boost the Performance of Your Apache Web Server

However, you want this change to be transparent to your users so that they are still able to access the docs at the usual URL.

In the following example, a file named assets.pdf has been moved from /var/www/html in 192.168.0.100(hostname: web) to the same location in 192.168.0.101 (hostname: web2).

In order for users to access this file when they browse to 192.168.0.100/assets.pdf, open Apache’s configuration file on 192.168.0.100 and add the following rewrite rule (or you can also add the following rule to your .htaccess file):

RewriteRule "^(/assets\.pdf$)" "http://192.168.0.101$1"  [R,L]

where $1 is a placeholder for anything that matches the regular expression inside parentheses.

Now save changes, don’t forget to restart Apache, and let’s see what happens when we attempt to access assets.pdf by browsing to 192.168.0.100/assets.pdf:

Suggested Read: 25 Useful ‘.htaccess’ Tricks for Websites

In the above below we can see that the request that was made for assets.pdf on 192.168.0.100 was actually handled by 192.168.0.101.

# tail -n 1 /var/log/apache2/access.log

In this article we have discussed how to perform a redirection to a resource that has been moved to a different server. To wrap up, I’d strongly suggest you take a look at the mod_rewrite guide and Apache redirect guide for future reference.

As always, feel free to use the comment form below if you have any concerns about this article. We look forward to hearing from you!

Source

SimpleHTTPServer is a python module which allows you to instantly create a web server or serve your files in a snap. Main advantage of python’s SimpleHTTPServer is you don’t need to install anything since you have python interpreter installed. You don’t have to worry about python interpreter because almost all Linux distributions, python interpreter come handy by default.

You also can use SimpleHTTPServer as a file sharing method. You just have to enable the module within the location of your shareable files are located. I will show you several demonstrations in this article by using various options.

Step 1: Check for Python Installation

1. Check whether python is installed in your server or not, by issuing below command.

# python –V 

OR

# python  --version

It will show you the version of the python interpreter you’ve got and it will give you an error message if it is not installed.

2. You’re lucky if it was there by default. Less work actually. If it was not installed by any chance, install it following below commands.

If you have a SUSE distribution, type yast in the terminal –> Go to Software Management –> Type ‘python’without quotes –> select python interpreter –> press space key and select it –> and then install it.

Simple as that. For that, you need to have SUSE ISO mounted and configured it as a repo by YaST or you can simple install python from the web.

If you’re using different operating systems like RHEL, CentOS, Debian, Ubuntu or other Linux operating systems, you can just install python using yum or apt.

In my case I use SLES 11 SP3 OS and python interpreter comes installed by default in it. Most of the case you won’t have to worry about installing python interpreter on your server.

Step 2: Create a Test Directory and Enable SimpleHTTPServer

3. Create a test directory where you don’t mess with system files. In my case I have a partition called /x01 and I have created a directory called tecmint in there and also I have added some test files for testing.

4. Your prerequisites are ready now. All you have to do is try python’s SimpleHTTPServer module by issuing below command within your test directory (In my case, /x01//).

# python –m SimpleHTTPServer

5. After enabling SimpleHTTPServer successfully, it will start serving files through port number 8000. You just have to open up a web browser and enter ip_address:port_number (in my case its 192.168.5.67:8000).

6. Now click on link 'tecmint' to browse files and directories of tecmint directory, see the screen below for reference.

7. SimpleHTTPServer serves your files successfully. You can see what has happened at the terminal, after you accessed your server through web browser by having a look at where you executed your command.

Step 3: Changing SimpleHTTPServer Port

8. By default python’s SimpleHTTPServer serves files and directories through port 8000, but you can define a different port number (Here I am using port 9999) as you desire with the python command as shown below.

# python –m SimpleHTTPServer 9999

Step 4: Serve Files from Different Location

9. Now as you tried it, you might like to serve your files in a specific location without actually going to the path.

As an example, if you are in your home directory and you want to server your files in /x01/tecmint/ directory without cd in to /x01/tecmint, Let’s see, how we will do this.

# pushd /x01/tecmint/; python –m SimpleHTTPServer 9999; popd;

Step 5: Serve HTML Files

10. If there’s a index.html file located in your serving location, python interpreter will automatically detect it and serve the html file instead of serving your files.

Let’s have a look at it. In my case I include a simple html script in the file named index.html and locate it in /x01/tecmint/.

<html>
<header><title>TECMINT</title></header>
<body text="blue"><H1>
Hi all. SimpleHTTPServer works fine.
</H1>
<p><a href="https://www.tecmint.com">Visit TECMINT</a></p>
</body>
</html>

Now save it and run SimpleHTTPServer on /x01/tecmint and go to the location from a web browser.

# pushd /x01/tecmint/; python –m SimpleHTTPServer 9999; popd;

Very simple and handy. You can serve your files or your own html code in a snap. Best thing is you won’t have to worry about installing anything at all. In a scenario like you want to share a file with someone, you don’t have to copy the file to a shared location or making your directories shareable.

Just run SimpleHTTPServer on it and it is done. There is a few things you have to keep in mind when using this python module. When it serves files it runs on the terminal and prints out what happens in there. When you’re accessing it from the browser or download a file from it, it shows IP address accessed it and file downloaded etc. Very handy isn’t it?

If you want to stop serving, you will have to stop the running module by pressing ctrl+c. So now you know how to use python’s SimpleHTTPServer module as a quick solution to serve your files. Commenting below for the suggestions and new findings would be a great favour to enhance future articles and learn new things.

Reference Links

SimpleHTTPServer Docs

Source

Apache is a world’s most popular, cross platform HTTP web server that is commonly used in Linux and Unix platforms to deploy and run web applications or websites. Importantly, it’s easy to install and has a simple configuration as well.

Read Also: How to Hide Apache Version Number and Other Sensitive Info

In this article, we will show how to check Apache web server uptime on a Linux system using different methods/commands explained below.

1. Systemctl Utility

Systemctl is a utility for controlling the systemd system and service manager; it is used it to start, restart, stop services and beyond. The systemctl status sub-command, as the name states is used to view the status of a service, you can use it for the above purpose like so:

$ sudo systemctl status apache2	  #Debian/Ubuntu 
# systemctl status httpd	  #RHEL/CentOS/Fedora 

2. Apachectl Utilities

Apachectl is a control interface for Apache HTTP server. This method requires the mod_status (which displays info about the server is performing including its uptime) module installed and enabled (which is the default setting).

On Debian/Ubuntu

The server-status component is enabled by default using the file /etc/apache2/mods-enabled/status.conf.

$ sudo vi /etc/apache2/mods-enabled/status.conf

On RHEL/CentOS

To enable server-status component, create a file below.

# vi /etc/httpd/conf.d/server-status.conf

and add the following configuration.

<Location "/server-status">
    SetHandler server-status
    #Require  host  localhost		#uncomment to only allow requests from localhost 
</Location>

Save the file and close it. Then restart the web server.

# systemctl restart httpd

If you are primarily using a terminal, then you also need a command line web browser such as lynx or links.

$ sudo apt install lynx		#Debian/Ubuntu
# yum install links		#RHEL/CentOS

Then run the command below to check the Apache service uptime:

$ apachectl status

Alternatively, use the URL below to view the Apache web server status information from a graphical web browser:

http://localhost/server-status
OR
http:SERVER_IP/server-status

3. ps Utility

ps is a utility which shows information concerning a selection of the active processes running on a Linux system, you can use it with grep command to check Apache service uptime as follows.

Here, the flag:

• -e – enables selection of every processes on the system.
• -o – is used to specify output (comm – command, etime – process execution time and user – process owner).

# ps -eo comm,etime,user | grep apache2
# ps -eo comm,etime,user | grep root | grep apache2
OR
# ps -eo comm,etime,user | grep httpd
# ps -eo comm,etime,user | grep root | grep httpd

The sample output below shows that apache2 service has been running for 4 hours, 10 minutes and 28 seconds (only consider the one started by root).

Lastly, check out more useful Apache web server guides:

1. 1. 13 Apache Web Server Security and Hardening Tips
   2. How to Check Which Apache Modules are Enabled/Loaded in Linux
   3. 5 Tips to Boost the Performance of Your Apache Web Server
   4. How to Password Protect Web Directories in Apache Using .htaccess File

In this article, we showed you three different ways to check Apache/HTTPD service uptime on a Linux system. If you have any questions or thoughts to share, do that via the comment section below.

Source

Netdata is a free open source, simple yet powerful, and effective real-time system performance monitoring tool for Linux, FreeBSD and MacOS. It supports various plugins for monitoring general server status, applications, web services such as Apache or Nginx HTTP server and so much more.

Read Also: How to Monitor Nginx Performance Using Netdata on CentOS 7

In this article, we will explain how to monitor Apache HTTP server performance using Netdata performance monitoring tool on a CentOS 7 or RHEL 7 distribution. At the end of this article, you will be able to watch visualizations of requests, bandwidth, workers, and other Apache server metrics.

Requirements:

1. A CentOS 7 Server or RHEL 7 Server with Minimal Install.
2. Apache HTTP server installation with mod_status module enabled.

Step 1: Install Apache on CentOS 7

1. First start by installing Apache HTTP server from the default software repositories using the YUM package manager.

# yum install httpd

2. After you have installed Apache web server, start it for the first time, check if it is up and running, and enable it to start automatically at system boot using following commands.

# systemctl start httpd
# systemctl enable httpd
# systemctl status httpd

3. If you are running a firewall for example firewalld, you need to open the ports 80 and 443 to allow web traffic to Apache via HTTP and HTTPS respectively, using the commands below.

# firewall-cmd --zone=public --permanent --add-port=80/tcp
# firewall-cmd --zone=public --permanent --add-port=443/tcp
# firewall-cmd --reload 

Step 2: Enable Mod_Status Module in Apache

4. In this step, you need to enable and configure mod_status module in Apache, this is required by Netdata for gathering server status information and statistics.

Open the file /etc/httpd/conf.modules.d/00-base.conf file using your favorite editor.

# vim /etc/httpd/conf.modules.d/00-base.conf

And ensure that the line below is uncommented to enable mod_status module, as shown in the screenshot.

5. Once you’ve enabled mod_status, next you need to create a server-status.conf configuration file for the Apache server status page.

# vim /etc/httpd/conf.d/server-status.conf

Add the following configuration inside the file.

<Location "/server-status">
    SetHandler server-status
    #Require host localhost           #uncomment to only allow requests from localhost 
</Location>

Save the file and close. Then restart the Apache HTTPD service.

# systemctl restart httpd

6. Next, you need to verify that the Apache server status and statistics page is working well by using a command-line web browser such as lynx as shown.

# yum install lynx
# lynx http://localhost/server-status   

Step 3: Install Netdata on CentOS 7

7. Fortunately, there is a kickstarter shell script for painlessly installing netdata from its github repository. This one-liner script downloads a second script which checks your Linux distribution and installs the required system packages for building netdata, then downloads the latest netdata source tree; builds and installs it on your server.

You can start the kickstarter script as shown, the all flag allows for installing required packages for all netdata plugins including the ones for Apache HTTP server.

# bash <(curl -Ss https://my-netdata.io/kickstart.sh) all

Note that if your not administering your system as root, you will be prompted to enter your user password for sudo command, and you will also be asked to confirm a number of functions by pressing [Enter].

8. Once the script has completed building and installing netdata, it will automatically start the netdata service via systemd service manager and enables it to start at system boot.

By default, netdata listens on port 19999, you will access the web UI using this port. So, open port 19999 in the firewall to access the netdata web UI.

# firewall-cmd --permanent --add-port=19999/tcp
# firewall-cmd --reload 

Step 4: Configure Netdata to Monitor Apache Performance

9. The netdata configuration for Apache plugin is /etc/netdata/python.d/apache.conf, this file is written in YaML format, you can open it using your favorite editor.

# vim /etc/netdata/python.d/apache.conf

The default configuration is just enough to get you started with monitoring your Apache HTTP server.

However, if you have read the documentation, and made any changes to it, restart the netdata service to effect the changes.

# systemctl restart netdata 

Step 5: Monitor Apache Performance Using Netdata

10. Next, open a web browser and use the following URL to access the netdata web UI.

http://domain_name:19999
OR
http://SERVER_IP:19999

From the netdata dashboard, search for “Apache local” on the right hand side list of plugins, and click on it to start monitoring your Apache server. You will be able to watch visualizations of requests, bandwidth, workers, and other server statistics, as shown in the following screenshot.

Netdata Github repository: https://github.com/firehol/netdata

That’s all! In this article, we’ve explained how to monitor Apache performance using Netdata on CentOS 7. If you have any questions or additional thoughts to share, please reach us via the comment form below.

Source

Nginx is a free open source, high-performance, reliable, scalable and fully extensible web server, load balancer and reverse proxy software. It has a simple and easy-to-understand configuration language. It also supports a multitude of modules both static (which have existed in Nginx since the first version) and dynamic (introduced in version 1.9.11).

One of the important modules in Nginx is the ngx_http_stub_status_module module which provides access to basic Nginx status information via a “status page”. It shows information such as total number of active client connections, those accepted, and those handled, total number of requests and number of reading, writing and waiting connections.

Read Also: Amplify – NGINX Monitoring Made Easy

On most Linux distributions, the Nginx version comes with the ngx_http_stub_status_module enabled. You can check out if the module is already enabled or not using following command.

# nginx -V 2>&1 | grep -o with-http_stub_status_module

If you see --with-http_stub_status_module as output in the terminal, means the status module is enabled. If the above command returns no output, you need to compile NGINX from source using the –with-http_stub_status_module as configuration parameter as shown.

# wget http://nginx.org/download/nginx-1.13.12.tar.gz
# tar xfz nginx-1.13.12.tar.gz
# cd nginx-1.13.12/
# ./configure --with-http_stub_status_module
# make
# make install

After verifying the module, you will also need to enable stub_status module in the NGINX configuration file /etc/nginx/nginx.conf to set up a locally reachable URL (e.g., http://www.example.com/nginx_status) for the status page.

location /nginx_status {
 	stub_status;
 	allow 127.0.0.1;	#only allow requests from localhost
 	deny all;		#deny all other hosts	
 }

Make sure to replace 127.0.0.1 with your server’s IP address and also make sure that this page accessible to only you.

After making configurations changes, make sure to check nginx configuration for any errors and restart the nginx service to effect the recent changes using following commands.

# nginx -t
# nginx -s reload 

After reloading nginx server, now you can visit the Nginx status page at the below URL using curl program to see your metrics.

# curl http://127.0.0.1/nginx_status
OR
# curl http://www.example.com/nginx_status

Important: The ngx_http_stub_status_module module has been superseded by the ngx_http_api_modulemodule in Nginx 1.13.0 version.

Read Also: How to Enable PHP-FPM Status Page in Nginx

That’s all! In this article, we have showed how to enable Nginx status page in Linux. Use the comment form below to ask any questions.

Source

Managers of web projects often need to protect their work one way or another. Often people ask how to password protect their website while it is still in development.

In this tutorial, we are going to show you a simple, but effective technique how to password protected web directory when running Nginx as web server.

In case you are using Apache web server, you can check our guide for password protecting a web directory:

1. Password Protect Web Directories in Apache

Requirements

To complete the steps in this tutorial, you will need to have:

• Nginx web server installed
• Root access to the server

Step 1: Create User and Password

1. To password protect our web directory, we will need to create the file that will contain our encrypted username and password.

When using Apache, you can use the “htpasswd” utility. If you have that utility installed on your system, you can use this command to generate the password file:

# htpasswd -c /path/to/file/.htpasswd username

When running this command, you will be asked to set a password for the above user and after that the .htpasswd file will be created in the specified directory.

2. If you don’t have that tool installed, you can create the .htpasswd file manually. The file should have the following syntax:

username:encrypted-password:comment

The username that you will use depends on you, choose whatever you like.

The more important part is the way that you will generate the password for that user.

Step 2: Generate Encrypted Password

3. To generate the password, use Perl’s integrated “crypt” function.

Here is an example of that command:

# perl -le 'print crypt("your-password", "salt-hash")'

A real life example:

# perl -le 'print crypt("#12Dfsaa$fa", "1xzcq")'

Now open a file and put your username and the generated in string it, separated with semicolon.

Here is how:

# vi /home/tecmint/.htpasswd

Put your username and password. In my case it looks like this:

tecmint:1xV2Rdw7Q6MK.

Save the file by hitting “Esc” followed by “:wq”.

Step 3: Update Nginx Configuration

4. Now open and edit the Nginx configuration file associated with the site you are working on. In our case we will use the default file at:

# vi /etc/nginx/conf.d/default.conf       [For CentOS based systems]
OR
# vi /etc/nginx/nginx.conf                [For CentOS based systems]


# vi /etc/nginx/sites-enabled/default     [For Debian based systems]

In our example, we will password protect the directory root for nginx, which is: /usr/share/nginx/html.

5. Now add the following two lines section under the path you wish to protect.

auth_basic "Administrator Login";
auth_basic_user_file /home/tecmint/.htpasswd;

Now save the file and restart Nginx with:

# systemctl restart nginx
OR
# service nginx restart

6. Now copy/paste that IP address in your browser and you should be asked for password:

That’s it! Your main web directory is now protected. When you want to remove the password protection on the site, simply remove the two lines that you just added to .htpasswd file or use the following command to remove the added user from a password file.

# htpasswd -D /path/to/file/.htpasswd username

Source

Have you ever encountered situations where one application dominated you all network bandwidth? If you have ever been in a situation where one application ate all your traffic, then you will value the role of the trickle bandwidth shaper application. Either you are a system admin or just a Linux user, you need to learn how to control the upload and download speeds for applications to make sure that your network bandwidth is not burned by a single application.

What is Trickle?

Trickle is a network bandwidth shaper tool that allows us to manage the upload and download speeds of applications in order to prevent any single one of them to hog all (or most) of the available bandwidth. In few words, trickle lets you control the network traffic rate on a per-application basis, as opposed to per-user control, which is the classic example of bandwidth shaping in a client-server environment, and is probably the setup we are more familiar with.

How Trickle Works?

In addition, trickle can help us to define priorities on a per-application basis, so that when overall limits have been set for the entire system, priority apps will still get more bandwidth automatically. To accomplish this task, trickle sets traffic limits to the way in which data is sent to, and received from, sockets using TCP connections. We must note that, other than the data transfer rates, trickle does not modify in any way the behavior of the process it is shaping at any given moment.

What Can’t Trickle do?

The only limitation, so to speak, is that trickle will not work with statically linked applications or binaries with the SUID or SGID bits set since it uses dynamic linking and loading to place itself between the shaped process and its associated network socket. Trickle then acts as a proxy between these two software components.

Since trickle does not require superuser privileges in order to run, users can set their own traffic limits. Since this may not be desirable, we will explore how to set overall limits that system users cannot exceed. In other words, users will still be able to manage their traffic rates, but always within the boundaries set by the system administrator.

In this article we will explain how to limit the network bandwidth used by applications in a Linux server with trickle. To generate the necessary traffic, we will use ncftpput and ncftpget (both tools are available by installing ncftp) on the client (CentOS 7 server – dev1: 192.168.0.17), and vsftpd on the server (Debian Wheezy 7.5 – dev2: 192.168.0.15) for demonstration purposes. The same instructions also works on RedHat, Fedora and Ubuntu based systems.

Prerequisites

1. For RHEL/CentOS 7/6, enable the EPEL repository. Extra Packages for Enterprise Linux (EPEL) is a repository of high-quality free and open-source software maintained by the Fedora project and is 100% compatible with its spinoffs, such as Red Hat Enterprise Linux and CentOS. Both trickle and ncftp are made available from this repository.

2. Install ncftp as follows:

# yum update && sudo yum install ncftp		[On RedHat based systems]
# aptitude update && aptitude install ncftp	[On Debian based systems]	

3. Set up a FTP server in a separate server. Please note that although FTP is inherently insecure, it is still widely used in cases when security in uploading or downloading files is not needed. We are using it in this article to illustrate the bounties of trickle and because it shows the transfer rates in stdout on the client, and we will leave the discussion of whether it should or should not be used for another date and time :).

# yum update && yum install vsftpd 		[On RedHat based systems]
# aptitude update && aptitude install vsftpd 	[On Debian based systems]

Now, edit the /etc/vsftpd/vsftpd.conf file on the FTP server as follows:

anonymous_enable=NO
local_enable=YES
chroot_local_user=YES
allow_writeable_chroot=YES

After that, make sure to start vsftpd for your current session and to enable it for automatic start on future boots:

# systemctl start vsftpd 		[For systemd-based systems]
# systemctl enable vsftpd
# service vsftpd start 			[For init-based systems]
# chkconfig vsftpd on

4. If you chose to set up the FTP server in a CentOS/RHEL 7 droplet with SSH keys for remote access, you will need a password-protected user account with the appropriate directory and file permissions for uploading and downloading the desired content OUTSIDE root’s home directory.

You can then browse to your home directory by entering the following URL in your browser. A login window will pop up prompting you for a valid user account and password on the FTP server.

ftp://192.168.0.15

If the authentication succeeds, you will see the contents of your home directory. Later in this tutorial you will be able to refresh that page to display the files that have been uploaded during previous steps.

How to Install Trickle in Linux

1. Install trickle via yum or aptitude.

To ensure a successful installation, it is considered good practice to make sure the currently installed packages are up-to-date (using yum update) before installing the tool itself.

# yum -y update && yum install trickle 		        [On RedHat based systems]
# aptitude -y update && aptitude install trickle 	[On Debian based systems]

2. Verify whether trickle will work with the desired binary.

As we explained earlier, trickle will only work with binaries using dynamic, or shared, libraries. To verify whether we can use this tool with a certain application, we can use the well-known ldd utility, where ldd stands for list dynamic dependencies. Specifically, we will look for the presence of glibc (the GNU C library) in the list of dynamic dependencies of any given program because it is precisely that library which defines the system calls involved in communication through sockets.

Run the following command against a given binary to see if trickle can be used to shape its bandwidth:

# ldd $(which [binary]) | grep libc.so

For example,

# ldd $(which ncftp) | grep libc.so

whose output is:

# libc.so.6 => /lib64/libc.so.6 (0x00007efff2e6c000)

The string between brackets in the output may change from system to system and even between subsequent runs of the same command, since it represents the load address of the library in physical memory.

If the above command does not return any results, it means that the binary it was run against does not use libcand thus trickle cannot be used as bandwidth shaper in that case.

Learn How to Use Trickle

The most basic usage of trickle is in standalone mode. Using this approach, trickle is used to explicitly define the download and upload speeds of a given application. As we explained earlier, for the sake of brevity, we will use the same application for download and upload tests.

Running Trickle in Standalone Mode

We will compare the download and upload speeds with and without using trickle. The -d option indicates the download speed in KB/s, while the -u flag tells trickle to limit the upload speed by the same unit. In addition, we will use the -s flag, which specifies that trickle should run in standalone mode.

The basic syntax to run trickle in standalone mode is as follows:

# trickle -s -d [download rate in KB/s] -u [upload rate in KB/s]

In order to perform the following examples on your own, make sure to have trickle and ncftp installed on the client machine (192.168.0.17 in my case).

Example 1: Uploading a 2.8 MB PDF file with and without trickle.

We are using the freely-distributable Linux Fundamentals PDF file (available from here) for the following tests.

You can initially download this file to your current working directory with the following command:

# wget http://linux-training.be/files/books/LinuxFun.pdf 

The syntax to upload a file to our FTP server without trickle is as follows:

# ncftpput -u username -p password 192.168.0.15  /remote_directory local-filename 

Where /remote_directory is the path of the upload directory relative to username’s home, and local-filename is a file in your current working directory.

Specifically, without trickle we get a peak upload speed of 52.02 MB/s (please note that this is not the real average upload speed, but an instant starting peak), and the file gets uploaded almost instantly:

# ncftpput -u username -p password 192.168.0.15  /testdir LinuxFun.pdf 

Output:

LinuxFun.pdf:                                        	2.79 MB   52.02 MB/s

With trickle, we will limit the upload transfer rate at 5 KB/s. Before uploading the file for the second time, we need to delete it from the destination directory; otherwise, ncftp will inform us that the file at the destination directory is the same that we are trying to upload, and will not perform the transfer:

# rm /absolute/path/to/destination/directory/LinuxFun.pdf 

Then:

# trickle -s -u 5 ncftpput -u username -p password 111.111.111.111 /testdir LinuxFun.pdf 

Output:

LinuxFun.pdf:                                        	2.79 MB	4.94 kB/s

In the example above, we can see that the average upload speed dropped to ~5 KB/s.

Example 2: Downloading the same 2.8 MB PDF file with and without trickle

First, remember to delete the PDF from the original source directory:

# rm /absolute/path/to/source/directory/LinuxFun.pdf 

Please note that the following cases will download the remote file to the current directory in the client machine. This fact is indicated by the period (‘.‘) that appears after the IP address of the FTP server.

Without trickle:

# ncftpget -u username -p  password 111.111.111.111 . /testdir/LinuxFun.pdf 

Output:

LinuxFun.pdf:                                        	2.79 MB  260.53 MB/s

With trickle, limiting the download speed at 20 KB/s:

# trickle -s -d 30 ncftpget -u username -p password 111.111.111.111 . /testdir/LinuxFun.pdf 

Output:

LinuxFun.pdf:                                        	2.79 MB   17.76 kB/s

Running Trickle in Supervised [unmanaged] Mode

Trickle can also run in unmanaged mode, following a series of parameters defined in /etc/trickled.conf. This file defines how trickled (the daemon) behaves and manages trickle.

In addition, if we want to set global settings to be used, overall, by all applications, we will need to use the trickled command. This command runs the daemon and allows us to define download and upload limits that will be shared by all the applications run through trickle without us needing to specify limits each time.

For example, running:

# trickled -d 50 -u 10

Will cause that the download and upload speeds of any application run through trickle be limited to 30 KB/s and 10 KB/s, respectively.

Please note that you can check at any time whether trickled is running and with what arguments:

# ps -ef | grep trickled | grep -v grep

Output:

root 	16475 	1  0 Dec24 ?    	00:00:04 trickled -d 50 -u 10

# wget http://media2.ldscdn.org/assets/missionary/our-people-2014/2014-00-1460-he-is-the-gift-360p-eng.mp4 

# trickled -d 30 -u 10

# ncftpput -u username -p password 192.168.0.15 /testdir 2014-00-1460-he-is-the-gift-360p-eng.mp4 

2014-00-1460-he-is-the-gift-360p-eng.mp4:           	18.53 MB   36.31 MB/s

# trickle ncftpput -u username -p password 192.168.0.15 /testdir 2014-00-1460-he-is-the-gift-360p-eng.mp4 

2014-00-1460-he-is-the-gift-360p-eng.mp4:           	18.53 MB	9.51 kB/s

# ncftpget -u username -p password 192.168.0.15 . /testdir/2014-00-1460-he-is-the-gift-360p-eng.mp4 

2014-00-1460-he-is-the-gift-360p-eng.mp4:           	18.53 MB  108.34 MB/s

# trickle ncftpget -u username -p password 111.111.111.111 . /testdir/2014-00-1460-he-is-the-gift-360p-eng.mp4 

2014-00-1460-he-is-the-gift-360p-eng.mp4:           	18.53 MB   29.28 kB/s

[service]
Priority = <value>
Time-Smoothing = <value>
Length-Smoothing = <value>

[ssh]
Priority = 1
Time-Smoothing = 0.1
Length-Smoothing = 2

[ftp]
Priority = 2
Time-Smoothing = 1
Length-Smoothing = 3

The command you’ll want to use to get the actual size of a directory is du which is short for “disk usage”. We’ll show you how to use this command.

Getting the Size of a Directory

The du command displays the amount of file space used by the specified files or directories. If the specified path is a directory, du will summarize disk usage of each file and subdirectory in that directory. If no path is specified, du will report the disk usage of the current working directory.

If you run du without any option it will display the disk usage the specified directory and each of its subdirectories in bytes.

In most cases, you would want to display only the space occupied by the directory in a human-readable format. For example, to get the total size of the /var directory, you would run the following command:

sudo du -sh /var

The output will look something like this.

85G	/var

Let’s explain the command and its arguments:

• The command starts with sudo because most of the files and directories inside the /var directory are owned by the root user and are not readable by the regular users. If you omit sudo the du command will print “du: cannot read directory”.
• s – Display only the total size of the specified directory, do not display file size totals for subdirectories.
• h – Print sizes in a human-readable format (h).
• /var – The path to the directory you want to get the size.

What if you want to display the disk usage of the first-level subdirectories. You have two options, the first one is to use the asterisk symbol as shown below which means “everything that doesn’t start with a period (.)“. The c switch tells du to print a grand total of all sizes:

sudo du -shc /var/*

.0G	/var/cache
24K	/var/db
4.0K	/var/empty
4.0K	/var/games
77G	/var/lib
4.0K	/var/local
0	/var/lock
3.3G	/var/log
0	/var/mail
4.0K	/var/opt
0	/var/run
196K	/var/spool
28K	/var/tmp
85G	total

Another option is to use the --max-depth switch and specify the subdirectories level:

sudo du -h --max-depth=1 /var

77G	  /var/lib
24K	  /var/db
4.0K	/var/empty
4.0K	/var/local
4.0K	/var/opt
196K	/var/spool
4.0K	/var/games
3.3G	/var/log
5.0G	/var/cache
28K	/var/tmp
85G	/var
85G	total

By default, the du utility shows the disk space used by the directory or file. The “apparent size” of a file is how much data is actually in the file.

To find the apparent size of a directory use the --apparent-size switch.

sudo du -sh --apparent-size /var

When you transfer a directory via SCP, Rsync or SFTP the amount of data that will be transferred over the network is the apparent size of the files. This is why the size of space on the disk that is used on the source when displayed with du (without --apparent-size) will not be the same as the size on the target.

The du command can also be combined with other commands with pipes. For example, to print the 5 largest directories in the /var directory you would use:

sudo du -h /var/ | sort -rh | head -5

85G	/var/
77G	/var/lib
75G	/var/lib/libvirt/images
75G	/var/lib/libvirt
5.0G	/var/cache/pacman/pkg

Conclusion

In this tutorial, you learned how to get the size of a directory using the du command. If you have any question or remark, please leave a comment below.

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