Guide to Unix/Commands/System Information
uptime
edituptime tells you how long the computer has been running since its last reboot or power-off.
Example:
$ uptime 22:27:49 up 10:14, 2 users, load average: 0.03, 0.32, 0.28
Links:
- uptime, freebsd.org
- 21.7 uptime in GNU Coreutils manual, gnu.org
uname
edituname displays the system information such as hardware platform,system name and processor, Operating System type.
Example:
$ uname -a Linux DarkBox 2.4.27-1-k6 #1 Wed Apr 14 19:00:29 UTC 2004 i586 GNU/Linux
Links:
- uname, opengroup.org
- uname, freebsd.org
- 21.4 uname in GNU Coreutils manual, gnu.org
dmesg
editdmesg display the messages from the kernel, since boot.
Example:
$ dmesg
Tips:
While a UNIX system is booting, usually a lot of messages flash on the console screen in rapid succession; to view those messages after the system is booted, use the following command:
$ dmesg | less
Using a command option, dmesg can filter the kernel messages, based on priority. The '-n 1' arguments will display only the panic messages:
$ dmesg -n 1
Links:
free
editfree display used and free memory
Example:
$ free
total used free shared buffers cached
Mem: 123260 119540 3720 0 8752 58096
-/+ buffers/cache: 52692 70568
Swap: 369452 63212 306240
Display in human readable form using MegaByte block sizes:
$ free -m
total used free shared buffers cached
Mem: 120 116 3 0 8 56
-/+ buffers/cache: 51 68
Swap: 360 61 299
Tips: Display system memory usage every 5 seconds, use Ctl+c to exit:
$ free -m -s 5
total used free shared buffers cached
Mem: 120 116 3 0 8 56
-/+ buffers/cache: 51 68
Swap: 360 61 299
total used free shared buffers cached Mem: 120 116 3 0 8 55 -/+ buffers/cache: 52 68 Swap: 360 61 299
Links:
- free, manpages.ubuntu.com
vmstat
editvmstat displays a compact summary of overall system activity (processes, memory, and cpu information).
Example:
$ vmstat procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 2 0 63108 4484 7432 56480 8 11 93 45 1110 622 41 11 48 0
Tips: Print out vmstat summaries every two seconds, for five iterations.
$ vmstat -n 2 5 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 1 0 63100 5172 7440 55892 8 10 90 44 1110 622 41 10 49 0 2 0 63100 5168 7440 55892 0 0 0 0 1120 559 32 3 65 0 1 0 63100 5160 7440 55892 0 0 0 0 1111 499 8 6 86 0 1 0 63100 5160 7440 55892 0 0 0 0 1113 505 12 3 85 0 1 0 63100 5168 7440 55892 0 0 0 0 1121 532 20 3 77 0
Links:
top
edittop displays system process in real time
Example:
$ top Tasks: 50 total, 2 running, 45 sleeping, 2 stopped, 1 zombie Cpu(s): 40.9% user, 10.5% system, 0.0% nice, 48.7% idle Mem: 123260k total, 119508k used, 3752k free, 7420k buffers Swap: 369452k total, 63036k used, 306416k free, 57212k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5340 arky 15 0 968 968 780 R 13.8 0.8 0:00.22 top
1408 root 6 -10 23712 6692 3252 S 1.5 5.4 3:39.58 [XFree86]
1 root 8 0 500 472 448 S 0.0 0.4 0:00.31 init [2]
2 root 9 0 0 0 0 S 0.0 0.0 0:01.60 [keventd]
3 root 19 19 0 0 0 S 0.0 0.0 0:00.02 [ksoftirqd_CPU0]
4 root 9 0 0 0 0 S 0.0 0.0 0:07.03 [kswapd]
5 root 9 0 0 0 0 S 0.0 0.0 0:00.00 [bdflush]
6 root 9 0 0 0 0 S 0.0 0.0 0:00.44 [kupdated]
154 root 9 0 0 0 0 S 0.0 0.0 0:00.00 [khubd]
562 root 9 0 604 588 508 S 0.0 0.5 0:05.09 /sbin/syslogd
565 root 9 0 1152 492 448 S 0.0 0.4 0:01.24 /sbin/klogd -c 3
.........
Links:
df
editdf reports the amount of free disk space available on each partition.
$ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/md0 5763508 207380 5263352 4% / /dev/md1 78819376 13722288 61093296 19% /home /dev/md4 23070564 4309572 17589056 20% /usr /dev/md2 5763508 1757404 3713328 33% /var /dev/md3 2877756 334740 2396832 13% /tmp
To report the number of free i-nodes
$ df -i
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/hda3 321952 32558 289394 11% /
/dev/hda2 67320 67 67253 1% /boot
/dev/mapper/vg00-home
372352 34227 338125 10% /home
/dev/mapper/vg00-tmp 242784 11649 231135 5% /tmp
/dev/mapper/vg00-usr 1821568 208669 1612899 12% /usr
/dev/mapper/vg00-var 1282560 75704 1206856 6% /var
Reports disk usage in human readable format with block-sizes in Kilo,Mega,Gigabytes. This option is specific for Wikipedia:GNU version of df.
$ df -h Filesystem Size Used Avail Use% Mounted on /dev/hda1 2.3G 2.1G 133M 95% / tmpfs 61M 8.0K 61M 1% /dev/shm /dev/hda2 2.0G 1.8G 113M 94% /usr
In some of Unix systems (SYS V family i.e. HP-UX) df displays the information in a different way:
$ df /home (/dev/vg01/lvol2 ): 262478 blocks 2647709 i-nodes /tmp (/dev/vg00/lvol5 ): 952696 blocks 125941 i-nodes /usr (/dev/vg00/lvol6 ): 132842 blocks 17633 i-nodes /var (/dev/vg00/lvol7 ): 131704 blocks 17288 i-nodes /stand (/dev/vg00/lvol1 ): 47548 blocks 13390 i-nodes / (/dev/vg00/lvol3 ): 160772 blocks 21215 i-nodes
In such cases try to use bdf command.
Links:
- df, opengroup.org
- df man page, man.cat-v.org
- 14.1 df in GNU Coreutils manual, gnu.org
hostname
edithostname displays and set system host name
Example:
Display the host name:
$ hostname Darkstar
Display the IP address of the system:
$ hostname -i 61.95.196.52
Set the host name of the system to 'DarkHorse':
$ hostname DarkHorse DarkHorse
Links:
- hostname, freebsd.org
- 21.5 hostname in GNU Coreutils manual, gnu.org