如何使用grep只获取一行的一部分

Question

when i try to send command ifconfig im getting this

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

how to get from this only part of lines for example

ESSID:""test
Frequency:2.412 GHz

Answer 1

Given your actual paste (and disregarding the malformed sample output):

$ 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

it's really just an extended RegEx, and grep's -o flag to ONLY output the exact match, rather than the matching line.