监视一组文件中的更改，并在更改时对其执行命令 [英] Monitor a set of files for changes and execute a command on them when they do

问题描述

我想到的（命令行）界面如下：

The (command line) interface I have in mind is like so:

watching FILE+ do COMMAND [ARGS] (and COMMAND [ARGS])*

任何出现 {}的地方 COMMAND 中的code>将替换为已更改文件的名称。请注意， do 和 和是关键字。

Where any occurrence of "{}" in COMMAND is replaced with the name of the file that changed. And note that "do" and "and" are keywords.

例如：

> watching foo.txt bar.txt do scp {} somewhere.com:. and echo moved {} to somewhere

或：

> watching foo.c do gcc foo.c and ./a.out

我不愿意该接口。我将添加执行此操作的脚本作为答案，看看是否有人有更好的方法或改进它的方法。

I'm not wedded to that interface though. I'll add my script that does that as an answer and see if anyone has anything better or ways to improve it.

推荐答案

#!/usr/bin/perl
# Run some commands whenever any of a set of files changes (see USAGE below).
# Example:
# ./watching.pl foo.txt bar.txt do scp foo.txt remote.com:. and cat bar.txt
# To only do something to the file that changed, refer to it as {}.

$| = 1;  # autoflush

my $p = position("do", @ARGV); # position of 1st occurrence of "do" in @ARGV.
if (@ARGV < 3 || $p == -1 || !($p >= 1 && $p < $#ARGV)) {
  die "USAGE: watching FILE+ do COMMAND [ARGS] (and COMMAND [ARGS])*\n";
}

my $cmdstr = join(' ', splice(@ARGV, $p+1));  # grab stuff after the "do"
my @cmds = split(/\s+and\s+/, $cmdstr);
pop(@ARGV);  # remove the "do" on the end.
my @targets = @ARGV;
print "Watching {", join(' ', @targets), "} do (", join('; ', @cmds), "):\n";

# initialize the %last hash for last mod time of each file.
for my $t (@targets) {
  ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
   $atime,$mtime,$ctime,$blksize,$blocks) = stat($t);
  $last{$t} = $mtime;
}

my $i = 1;
while(1) {
  if($i % (45*60) == 0) { print "."; }

  for my $t (@targets) {
    ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
     $atime,$mtime,$ctime,$blksize,$blocks) = stat($t);

    if ($mtime != $last{$t}) {
      print "\nCHANGE DETECTED TO $t\n";
      for (@cmds) { my $tmp = $_; $tmp =~ s/\{\}/$t/g; system($tmp); }
      $last{$t} = $mtime;
    }
  }
  sleep(1);
  $i++;
}


# Call like so: position($element, @list).
sub position {
  my $x = shift;
  if(@_==0) { return -1; }
  if($x eq $_[0]) { return 0; }
  shift;
  my $p = position($x,@_);
  if($p==-1) { return -1; }
  return 1+$p;
}

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