[SOLVED] Bash Populate array and ignore lines with certain characters

jtn703 · 11-19-2012, 03:29 PM

I'm trying to read a DNS file with a list of hosts into an array. I think I have the array populated, but I would like to ignore lines with certain chars, such as semicolon, at (@) sign, etc. I'm not sure how to do so. Can you point me in the right direction?

Right now, the below populates everything into an array. Thanks!

array=( $(ssh $USER@$DNS_SERVER "cat /var/cache/bind/dns_hosts | awk '{print \$1}'") )

echo ${array[@]}

jtn703 · 11-19-2012, 03:59 PM

I think I figured it out, but just in case anyone has better suggestions, I'm all ears:

array=( $(ssh $USER@$DNS_SERVER "cat /var/cache/bind/dns_hosts | grep -v ';' | grep -v '@' | awk '{print \$1}'") )

Thanks!

ntubski · 11-19-2012, 08:14 PM

awk generally subsumes grep's functionality:

Code:

grep -v ';' | grep -v '@' | awk '{print $1}'
## can be written as
awk '!/;|@/{print $1}'
## or
awk '!/[;@]/{print $1}'

Also, you have a Useless Use of Cat:

Code:

cat file | command
## can be written as
< file command
## when command is awk, you can also use
awk '{awk code}' file

So:

Code:

array=( $(ssh $USER@$DNS_SERVER "awk '!/[@;]/{print \$1}' /var/cache/bind/dns_hosts") )