[Bug 996435] Re: resolvconf uses awk but doesn't Depend on it

[Steve Langasek]

As for why using awk instead of grep: I haven't done any speed
comparisons between the two, but I found the echo_first_arg function
very non-idiomatic and think this is better done in-line with a standard
posix tool.

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https://bugs.launchpad.net/bugs/996435

Title:
  resolvconf uses awk but doesn't Depend on it

Status in “resolvconf” package in Ubuntu:
  Invalid

Bug description:
  After the latest bugfix (in versions 1.63ubuntu13 and 1.65ubuntu2) the
  difference between the Debian and Ubuntu lsattr-checking code in
  resolvconf.postinst is this:

  
  -echo_first_arg() { echo "$1" ; }
   is_immutable_file() {
   	[ "$1" ] || return 2
   	[ -e "$1" ] || return 1
   	[ ! -L "$1" ] || return 1
  -	which lsattr >/dev/null 2>&1 || return 2
  -	echo_first_arg $(lsattr "$1") | grep -sq i
  +
  +	ATTR=$(lsattr "$1" 2>/dev/null)
  +	[ -z "$ATTR" ] && return 1
  +	echo $ATTR | awk '$1 ~ /i/ { exit 0; }; { exit 1; }'
   }
   

  It isn't obvious to me why grep was replaced with awk here.  The
  resulting code is slower and not much more readable, so why change it?

  To suppress lsattr error messages it would have sufficed to do this:

  -	echo_first_arg $(lsattr "$1") | grep -sq i
  +	echo_first_arg $(lsattr "$1" 2>/dev/null) | grep -sq i

  I'll include this change in the next Debian version; but if you can
  explain to me why the awk code is better then I'll adopt that.

  A remaining issue is that the resolvconf package doesn't Depend on awk
  and awk is not Essential (although it is Depended upon by base-files
  which is Essential). Is this a problem?

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