ackerleytng has asked for the wisdom of the Perl Monks concerning the following question:

Hi!

I wish to read user input and the problem that I was facing was that pressing almost anything non-text on the keyboard produces these escape sequences on screen ^[[A etc that were interfering with my output.

To get around that, I used Term::Readline. Now I wish to maintain and access a history of past inputs. I read this post at http://stackoverflow.com/questions/14671797/how-to-use-termreadline-to-retrieve-command-history, which suggests that I install Term::Readline::Gnu.

Unfortunately, I don't have root access and so I can't install that module. I still keep getting ^[[A etc on my output. Any way to get the same functionality without installing stuff?

  • Comment on Simulating input history without Term::Readline::Gnu

Replies are listed 'Best First'.
Re: Simulating input history without Term::Readline::Gnu
by mtmcc (Hermit) on Jul 15, 2013 at 18:58 UTC
    What code are you using to read user input? Using <STDIN>, usually only the arrow characters give ^[[A on my system.

    The modules mentioned above can be useful, and Term::UI::History might be worth looking at.

    A simple method of recording history might be to just push the input to an array, for example:

    #!/usr/bin/perl 
use strict;
use warnings;

my @history;
my $text;
my $x;

print STDERR "Enter text ('q' to quit): ";
$text = <STDIN>;
chomp $text;
push (@history, "$text\n");

while ($text ne 'q')
    {
        print STDERR "Enter text ('q' to quit): ";
        $text = <STDIN>;
        chomp $text;
        push (@history, "$text\n");
    }

my $numberOfHistoryItems = @history;

print STDERR "For history, press 'h', else quit:";
my $history = <STDIN>;
chomp $history;

if ($history eq "h")
    {
        for($x = 0; $x < $numberOfHistoryItems; $x += 1)
            {
                print STDOUT "$history[$x]" if $numberOfHistoryItems >
+0;

            }
        print STDOUT "No history items\n" if $numberOfHistoryItems == 
+0;
    }

    [download]

    Although admittedly, that might get tedious and unwieldy if your script is long.

    -Michael
[reply]
[d/l]
[select]
      Yes, those characters appear when I press the arrow keys. I'll look into Term::UI::History, thanks! Your idea is great, but I wish I could do something like that without requiring the user to press enter before the input is interpreted. Ideally, it should work like how a terminal works.
[reply]
Re: Simulating input history without Term::Readline::Gnu
by rjt (Curate) on Jul 15, 2013 at 18:10 UTC
[reply]
      Thanks! I'll look into this. It's mostly that I don't have write access to those library folders and I was hoping to just get around it. Besides, in a testing environment on many systems, it's much easier to have my scripts portable and transferable onto the existing framework than to have to install CPAN modules every time I need to run a script...
[reply]

Back to Seekers of Perl Wisdom