until loop Perl

Shell Programming and Scripting
1

I am trying to print out a section of a file begining at the start and printng until a character is found.

My code and input file are below. This code is printing out every line except for the line with the character which is not what I want the out put should be a file with numbers 1-4.

Input file

1
2
3
4
*5
6
7
8

Code

while(<FILE>)
{
until(/\*/) {
print "\n$_\n";
last;
}
}
close(FILE);

Please provide a correction to the code or a better method.

Thanks

2 
$
$
$ cat f1
1
2
3
4
*5
6
7
8
$
$ perl -lne '$x=1 if /\*/; print if not $x' f1
1
2
3
4
$
$

tyler_durden

3

Thanks tyler_durden, can you please explain your code I think your seting $x to true if the line contains "*" and if not then it's false?

---------- Post updated at 12:13 PM ---------- Previous update was at 12:06 PM ----------

I think I got the concept. Set a variable to 1 if you hit this character if the variable is 0 by default then print

while(<FILE>)
{
  $x=1 if(/\*/);
  if($x==0){print;}
}

Thanks

4

$x is undefined at that point, but the equality condition is true which is why it prints.

You could do the same without a sentinel variable.

#perl -w
open(F, "f1") or die "Can't open f1: $!";
while (<F>) {
  unless (/\*/) {
    print;
  } else {
    last;
  }
}
close(F) or die "Can't close f1: $!";

or

#perl -w
open(F, "f1") or die "Can't open f1: $!";
$_ = <F>;
until (/\*/) {
  print;
  $_ = <F>;
}
close(F) or die "Can't close f1: $!";

come to mind.

tyler_durden