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Hi,
I will continue to explain Linux Commands for Beginners in this tutorial series.
You can read first article before this.
GNU/Linux Bash Commands Tutorial for Beginners -1 Working with Files and Directories
2. System commands
System commands in Linux are generally used to learn about time, calendar, cpu, disk and memory, or other necessary information about the system.
These commands are as follows.
- date
- cal
- uptime
- whereis
- which
- uname
- w
- whoami
- cat /proc/cpuinfo
- cat /proc/meminfo
date
With this command, you can display the current time and date of the system. Its use is as follows.
[[email protected] ~]# [[email protected] ~]# date Tue Sep 10 16:29:44 +03 2019 [[email protected] ~]#
cal
With this command, the system displays the current month as a 1-month calendar. This command can also take parameters. If you want to see a month of any year, you should type a command like the one below.
[[email protected] ~]# cal September 2019 Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 [[email protected] ~]# [[email protected] ~]# cal 5 1989 May 1989 Su Mo Tu We Th Fr Sa 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 [[email protected] ~]#
uptime
This command is used to display how long the machine has been running continuously. This command returns the user the current time, how long it has been running, the number of active users in the system, and the load performance of the system in the last minutes.
Usage and output are as follows.
[[email protected] ~]# uptime 16:29:54 up 1 day, 2:48, 5 users, load average: 0.05, 0.07, 0.11 [[email protected] ~]#
whereis
The executable file for a given file or command with this command indicates the location of the executable file or source files on the server.
Use of the command is as follows.
[[email protected] oradata]# whereis date date: /bin/date /usr/share/man/man1/date.1.gz /usr/share/man/man1p/date.1p.gz [[email protected] oradata]#
which
Gives the full path of Linux command on the server. Its use is as follows.
[[email protected] oradata]# which date /bin/date [[email protected] oradata]#
uname
With this command, the parameter to be entered as -a gives various information about the system such as your machine type, network host name and so on. usage and examples are as follows.
[[email protected] ~]# uname Linux [[email protected] ~]# [[email protected] ~]# [[email protected] ~]# uname -a Linux MehmetSalih 3.8.13-118.13.3.el6uek.x86_64 #2 SMP Fri Oct 21 14:30:26 PDT 2016 x86_64 x86_64 x86_64 GNU/Linux [[email protected] ~]# [[email protected] ~]# [[email protected] ~]# uname -i x86_64 [[email protected] ~]#
w
With this command, user can see who is active in the system and what he or she is doing. Its use is as follows.
whoami
With this command, the user who is currently logged in the system is displayed.
[[email protected] ~]# whoami root [[email protected] ~]# su - oracle [[email protected] ~]$ [[email protected] ~]$ whoami oracle [[email protected] ~]$
cat /proc/cpuinfo
This command provides the user with detailed information about the CPU. Use of the command is as follows.
Bu komut ile sistemi yöneten merkezi işlem birimi (Cpu) nin çalışması hakkında ayrıntılı bilgi kullanıcıya sunulur. Komutun kullanımı aşağıdaki gibidir.
[[email protected] ~]# cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 63 model name : Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz stepping : 2 microcode : 0x39 cpu MHz : 2499.998 cache size : 30720 KB physical id : 0 siblings : 4 core id : 0 cpu cores : 4 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 mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc eagerfpu pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm arat xsaveopt fsgsbase tsc_adjust bmi1 avx2 smep bmi2 invpcid bogomips : 4999.99 clflush size : 64 cache_alignment : 64 address sizes : 42 bits physical, 48 bits virtual power management: processor : 1 vendor_id : GenuineIntel ....................... .................... processor : 15 vendor_id : GenuineIntel cpu family : 6 model : 63 model name : Intel(R) Xeon(R) CPU E5-2680 v3 @ 2.50GHz stepping : 2 microcode : 0x39 cpu MHz : 2499.998 cache size : 30720 KB physical id : 3 siblings : 4 core id : 3 cpu cores : 4 apicid : 15 initial apicid : 15 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 mmx fxsr sse sse2 ss ht syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc eagerfpu pni pclmulqdq ssse3 fma cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm abm arat xsaveopt fsgsbase tsc_adjust bmi1 avx2 smep bmi2 invpcid bogomips : 4999.99 clflush size : 64 cache_alignment : 64 address sizes : 42 bits physical, 48 bits virtual power management: [[email protected] ~]#
cat /proc/meminfo
This command provides detailed information about the operation of RAM (Random Access Memory) in the server. Use of the command is as follows.
[[email protected] ~]# cat /proc/meminfo MemTotal: 49463392 kB MemFree: 171816 kB Buffers: 331572 kB Cached: 46352256 kB SwapCached: 27664 kB Active: 39452124 kB Inactive: 8347072 kB Active(anon): 39098508 kB Inactive(anon): 7994460 kB Active(file): 353616 kB Inactive(file): 352612 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 4194300 kB SwapFree: 1433652 kB Dirty: 492 kB Writeback: 0 kB AnonPages: 1091212 kB Mapped: 26328108 kB Shmem: 45977576 kB Slab: 739528 kB SReclaimable: 605408 kB SUnreclaim: 134120 kB KernelStack: 6152 kB PageTables: 377244 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 28925996 kB Committed_AS: 89343800 kB VmallocTotal: 34359738367 kB VmallocUsed: 247156 kB VmallocChunk: 34333911692 kB HardwareCorrupted: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 14208 kB DirectMap2M: 3131392 kB DirectMap1G: 49283072 kB [[email protected]MehmetSalih ~]#
I will continue to explain Linux commands tutorial series in the next article.
Do you want to learn Linux System Administration for Beginners, then read the following articles.
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