Linux Practice

https://www.kernel.org/

http://www.gnu.org/

Coreutils - GNU core utilities

https://www.gnu.org/software/coreutils/

System context

uname: Print system information

Print all information

$ uname -a
Linux debian-512mb-sgp1-01 3.16.0-4-amd64 #1 SMP Debian 3.16.43-2+deb8u2 (2017-06-26) x86_64 GNU/Linux

Print the kernel release

$ uname -r
3.16.0-4-amd64

Print the kernel version

$ uname -v
#1 SMP Debian 3.16.43-2+deb8u2 (2017-06-26)

hostname: Print or set system name

Get the hostname

$ hostname
mysql.example.com
$ cat /etc/hostname
mysql.example.com

Set the hostname. Note, that this is effective only until the next reboot. Edit /etc/hostname for permanent change.

$ hostname redis.example.com
$ hostname
redis.example.com
$ cat /etc/hostname
mysql.example.com

$ echo redis.example.com > /etc/hostname
$ reboot ## REBOOT!!! ##
$ hostname
redis.example.com

uptime: Print system uptime and load

uptime prints the current time, the system's uptime, the number of logged-in users and the current load average.

$ uptime
 03:48:42 up 28 min,  2 users,  load average: 0.00, 0.00, 0.00

# 读取系统平均负载。后面的分数，分母表示系统进程总数，分子表示正在运行的进程数，最后一个数字表示最近运行的进程 ID。
$ cat /proc/loadavg
0.00 0.00 0.00 1/74 1248

# 读取 CPU 核心数目
$ grep 'model name' /proc/cpuinfo | wc -l
1