Strip last period from a host string

Question

I am having a hard time figuring out how to strip the last period from a hostname …

current output:

domain.com.
suddomain.com.
domain.com.
subdomain.subdomain.com.
subdomain.com.

desired output:

domain.com
subdomain.com
domain.com
subdomain.subdomain.com

attempt 1:

print string[:-1]  #it works on some lines but not all

attempt 2:

 str = string.split('.')
 subd = '.'.join(str[0:-1])
 print subd    # does not work at all

code:

global DOMAINS

if len(DOMAINS) >= 1:
  for domain in DOMAINS:
    cmd = "dig @adonis.dc1.domain.com axfr %s |grep NS |awk '{print $1}'|sort -u |grep -v '^%s.$'" % (domain,domain)
    p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,   shell=True)
    string = p.stdout.read()
    string = string.strip().replace(' ','')
    if string:
      print string

Asked By: Simply Seth

||

Source

Answer 1

You do it like this:

hostname.rstrip('.')

where hostname is the string containing the domain name.

>>> 'domain.com'.rstrip('.')
'domain.com'
>>> 'domain.com.'.rstrip('.')
'domain.com'

Answered By: isedev

Answer 2

I gave up and just used sed instead ….

cmd = "dig @adonis.dc1.domain.com axfr %s |grep NS |awk '{print $1}' |sort -u |grep -v '^%s.$'|sed -e 's/.$//'"

Answered By: Simply Seth

Answer 3

The answer given by @isedev is somewhat incomplete in this specific use case. rstrip('.') will strip the trailing period from a string, however the string returned by subprocess will have a trailing newline character (0x0A) following the period which causes rstrip('.') to fail.

This is likely why OP gave up.

Consider the following python3 code:

print ('domain.'.rstrip('.'))

Works as perceived. However, adding a newline character to mimic shell output:

print ('domain.n'.rstrip('.'))

prints domain.

One way to manage this is to simply insert a strip() before the rstrip() call:

print ('domain.n'.strip().rstrip('.'))

which prints: domain

Always, always strip your shell output 🙂

Answered By: Nstevens

Strip last period from a host string

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