mjhjmtu

i want to print interface names only from iwconfig command

this is output of iwconfig:

wlp2s0 IEEE 802.11 ESSID:"CoreFragment" 
 Mode:Managed Frequency:2.442 GHz Access Point: 0C:D2:B5:55:DF:74 
 Bit Rate=72.2 Mb/s Tx-Power=22 dBm 
 Retry short limit:7 RTS thr:off Fragment thr:off
 Power Management:on
 Link Quality=55/70 Signal level=-55 dBm 
 Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
 Tx excessive retries:4 Invalid misc:6567 Missed beacon:0

enp3s0 no wireless extensions.

wlx00e02d01076f IEEE 802.11bgn ESSID:"Aleph_inCar" Nickname:"<WIFI@REALTEK>"
 Mode:Master Frequency:2.412 GHz Access Point: 00:E0:2D:01:07:6F 
 Bit Rate:72.2 Mb/s Sensitivity:0/0 
 Retry:off RTS thr:off Fragment thr:off
 Power Management:off
 Link Quality=4/100 Signal level=4/100 Noise level=0/100
 Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
 Tx excessive retries:0 Invalid misc:0 Missed beacon:0

lo no wireless extensions.

enx001e101f0000 no wireless extensions. 

I tried this :

iwconfig | grep ESSID | sed 's/"//g' | cut -f1 -d" " 

but i got no wireless extension also in output

i want to get output from iwconfig command only

how print wlp2s0,enp3s0,wlx00e02d01076f,enx001e101f0000 only...

Your command works perfectly. Simply redirect the STDERR output to STDOUT, so that grep and cut process them as you want:

iwconfig 2>&1 | grep ESSID | sed 's/"//g' | cut -f1 -d" " 

However, this method using grep, sed and cut is an overkill. A single grep can get you what you want as suggested in the update below.

UDPATE:

As per the edited question, and given that the user is using Ubuntu (and hence the grep supports Perl regex), here is one method:

iwconfig 2>&1 | grep -oP "^w+"