Re: [Help-nano] lock a file

[Trevor Cordes]

On  5 May, Justin Lecher wrote:
> Hello!
> 
> Is it possible to let nano lock the file which is opened for write 
> access on other session? On our server there was an accident where two 
> admins has opened the same file on discarded the changes of the other 
> with writing his own. Could this be avoid?

I wrote a wrapper script to do something like this.  YMMV!  Works for me
on recent Linux using recent perl (all Fedora 8).  Just always run using
this new command and you'll always be warned!

Enjoy!

cat /usr/local/script/pc
#!/usr/bin/perl -w
# (c) 2008 Trevor Eaton Cordes  address@hidden
# GPLv2, credit notice must be retained

use File::Basename;
use File::PathConvert qw(realpath);

$f=$ARGV[0] or die "Usage: pc file-to-edit\n";
$fbase=basename($f);
$freal=realpath(($f=~m#^/#?'':"$ENV{PWD}/").$f) or die;

$m='';
open(PS,'ps -efww|') or die;
while(<PS>) {
  if 
(m#^\S+\s+(\d+).*?\s+\d\d:\d\d:\d\d\s+nano(?:\s+-\S+)*\s+((?:/[^/]*?)*?$fbase\b)#)
 {
    $pid=$1;
    $munreal=$2;
    open(ENV,"ps --no-headers --pid $pid eww|") or die;
    $mwithenv=<ENV>;
    close(ENV);
    ($pwd)=($mwithenv=~m# PWD=(.*?)(?: ?[A-Z0-9]+=|$)#) or die "cannot find PWD 
$mwithenv";
    $mreal=realpath(($pwd=~m#^/#?'':"$pwd/").$munreal) or die "cannot parse 
real $pwd,$munreal***,".(($pwd=~m#^/#?'':"$pwd/").$munreal).'***';
    if ($freal eq $mreal) {
      $m=$_;
      last;
    }
  }
}
close(PS);

if ($m) {
  ($pts)=($m=~m#(pts/\d+)#) or die;
  print "already editing $f on $pts\n";
  print "writing ****'s to $pts\n";
  $s80='*'x80;
  system "echo '$s80\n$s80\n$s80' | write $ENV{LOGNAME} $pts";
  exit 1;
}

exec 'nano','-z','-w',$f;