linux - 如何使用 grep 只获取一行的一部分

Question

当我尝试发送命令 ifconfig 时，我得到了这个

ath0  IEEE 802.11ng  ESSID:"test"  Nickname:""
      Mode:Master  Frequency:2.412 GHz  Access Point: 00:00:00:00:00:00
      Bit Rate:0 kb/s   Tx-Power=-4 dBm   Sensitivity=16/16
      Retry:off   RTS thr:off   Fragment thr:off
      Encryption key:off
      Power Management:off
      Link Quality=0/94  Signal level=-96 dBm  Noise level=-96 dBm
      Rx invalid nwid:475654423  Rx invalid crypt:0  Rx invalid frag:0
      Tx excessive retries:0  Invalid misc:0   Missed beacon:0

例如如何从这部分行中获取

ESSID:""test
Frequency:2.412 GHz

Answer 1

考虑到您的实际粘贴(并忽略格式错误的示例输出):

$ cat ifconf 
ath0  IEEE 802.11ng  ESSID:"test"  Nickname:""
      Mode:Master  Frequency:2.412 GHz  Access Point: 00:00:00:00:00:00
      Bit Rate:0 kb/s   Tx-Power=-4 dBm   Sensitivity=16/16
      Retry:off   RTS thr:off   Fragment thr:off
      Encryption key:off
      Power Management:off
      Link Quality=0/94  Signal level=-96 dBm  Noise level=-96 dBm
      Rx invalid nwid:475654423  Rx invalid crypt:0  Rx invalid frag:0
      Tx excessive retries:0  Invalid misc:0   Missed beacon:0
$ grep -oE 'ESSID:"[^"]+"|Frequency:[^ ]+' ifconf
ESSID:"test"
Frequency:2.412

它实际上只是一个扩展的正则表达式，而 grep 的 -o 标志仅输出精确匹配，而不是匹配行。