CODEWITHSUNDEEP
linuxbashloopshttp-redirectterminal
Anonymous101
Anonymous101

Reputation: 13

redirect command error output to /dev/null

i run ( host ) command on a list of subdomain's to get the ip for each domain ... i want to ignore the not found: 3(NXDOMAIN) result i try with

for i in $(cat no-http.txt) ; do host $i 2>/dev/null; done

output :

e1792.dscx.akamaiedge.net has address 104.79.236.53
e1792.dscx.akamaiedge.net has IPv6 address 2a02:26f0:fa00:597::700
e1792.dscx.akamaiedge.net has IPv6 address 2a02:26f0:fa00:5a3::700
akamai-apigateway-warp3pl.tesla.com is an alias for akamai-apigateway-warp3pl.tesla.com.edgekey.net.
akamai-apigateway-warp3pl.tesla.com.edgekey.net is an alias for e1792.dscx.akamaiedge.net.
e1792.dscx.akamaiedge.net has address 104.79.236.53
e1792.dscx.akamaiedge.net has IPv6 address 2a02:26f0:fa00:5a3::700
e1792.dscx.akamaiedge.net has IPv6 address 2a02:26f0:fa00:597::700
Host olt.tesla.com not found: 3(NXDOMAIN)
^CHost kamai-apigateway-warp3pl.tesla.com not found: 3(NXDOMAIN)
Host kamai-apigateway-warpdashboardapi.tesla.com not found: 3(NXDOMAIN)

how i can redirect not found: replay to /dev/null

Upvotes: 0

Views: 136

Answers (2)

Léa Gris
Léa Gris

Reputation: 19655

The NOT found causes host to return 1 so test its return code.

#!/usr/bin/env sh

while read -r name; do
  if reply=$(host "$name"); then
    printf '%s\n' "$reply"
  fi
done <no-http.txt

Upvotes: 2

Barmar
Barmar

Reputation: 782130

The "not found" message isn't being written to stderr, so you can't filter it by redirecting.

You can use grep -v to filter it out.

for i in $(cat no-http.txt) ; do host "$i" ; done | grep -v 'not found'

Upvotes: 1

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