Linux fg bg jobs

Linux  fg bg             ，      （    ）              。              ，           ，            ；                           。

                ：

Ctrl+C

            ，  SHELL

Ctrl+Z

         ，        ，  SHELL

jobs

            ，         

&

     ，       &         

fg N

        N           ， %N

bg N

        N           

          ：

[maple@linux ~]$  ping baidu.com -a >/dev/null &
[1] 12879
[maple@linux ~]$ jobs
[1]+  Running                 ping baidu.com -a > /dev/null &
[maple@linux ~]$
[maple@linux ~]$ ping google.com -a >/dev/null
#Ctrl+Z
[2]+  Stopped                 ping google.com -a > /dev/null
[maple@linux ~]$ jobs
[1]-  Running                 ping baidu.com -a > /dev/null &
[2]+  Stopped                 ping google.com -a > /dev/null
[maple@linux ~]$
[maple@linux ~]$ fg 1
ping baidu.com -a > /dev/null
#Ctrl+Z
[1]+  Stopped                 ping baidu.com -a > /dev/null
[maple@linux ~]$ jobs
[1]+  Stopped                 ping baidu.com -a > /dev/null
[2]-  Stopped                 ping google.com -a > /dev/null
[maple@linux ~]$
[maple@linux ~]$ bg 2
[2]- ping google.com -a > /dev/null &
[maple@linux ~]$ jobs
[1]+  Stopped                 ping baidu.com -a > /dev/null
[2]-  Running                 ping google.com -a > /dev/null &
[maple@linux ~]$
[maple@linux ~]$ %2
ping google.com -a > /dev/null
#Ctrl+Z
[2]+  Stopped                 ping google.com -a > /dev/null
[maple@linux ~]$ jobs
[1]-  Stopped                 ping baidu.com -a > /dev/null
[2]+  Stopped                 ping google.com -a > /dev/null
[maple@linux ~]$
[maple@linux ~]$