What is check_http?
5 check_http examples
Syntax and Options
Related Commands
check_http plugin is used to verify the status of HTTP server (or HTTPS) that is running on a remote host. If you’ve installed Nagios from source, check_httpd command will be located in the /usr/local/nagios/libexec directory.
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What is split?
5 split examples
Syntax and Options
Related Commands
split command splits a single file into multiple files.
What is look?
3 look examples
Syntax and Options
Related Commands
look command is used to display strings that begin with the given strings.
In other words, look command can be used to check the spelling of a word, by giving the words prefix.
What is wc ?
3 wc examples
Syntax and Options
Related Commands
wc prints the number of lines, words and bytes in the given input. wc is the abbreviation of word count.
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What is whereis ?
3 whereis examples
Syntax and Options
Related Commands
Whereis command is used to find out where the binary, source, and man page files for a command is located.
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What is pmap ?
3 pmap examples
Syntax and Options
Related Commands
pmap displays the memory map of a process for the specified pid(s).
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What is eject ?
4 eject examples
Syntax and Options
Related Commands
eject command is mainly used to eject the CD / DVD tray. You can also close the tray using certain options.
eject command can be used to eject floppy disk, tape, or JAZ or ZIP disk. eject command can also be used to control the eject options.
If the device is mounted while trying to eject, it will be unmounted first before ejecting.
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What is iostat?
4 iostat examples
Syntax and Options
Related Commands
Iostat command reports CPU and I/O statistics. iostat command is used during performance analysis to narrow down the problematic areas in the system.
Sample output of iostat command and its explanation:
$ iostat
Linux 2.6.31-17-generic (sathiya-laptop) 05/25/10 _i686_ (1 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
25.99 0.78 7.43 12.77 0.00 53.03
Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn
sda 27.40 797.19 201.27 800902 202208
sr0 0.03 1.24 0.00 1248 0
The first line displays general information — Linux kernel version, hostname etc.,
Next two lines displays CPU statistics, in which the first 3 column displays average CPU usage. The 4th column displays the percentage of time the CPU were idle and waited for I/O response. 5th column displays percentage of waiting time of virtual CPU. 6th column displays the percentage of time the CPU is idle.
Remaining line displays the device utilization report. First line in that is headers, such as number of Transfer per second, number of blocks read per second, blocks write per second, total block reads, total block writes.
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What is shutdown?
5 shutdown examples
Syntax and Options
Related Commands
Shutdown the system in a safe way. You can shutdown the machine immediately, or schedule a shutdown using 24 hour format.
After bringing down the system, shutdown command halts or reboots the system according to the option that is specified. Only root user can execute shutdown command.
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What is md5sum?
5 md5sum examples
Syntax and Options
Related Commands
md5sum is a 128 bit checksum which will be unique for the same data provided. Use md5sum command to calculate and cross check the md5sum.
Two non identical files will never have the same md5sum. Typically, md5sum is used to cross verify the integrity of a file after downloading it from a website.
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