Shell Programming and Scripting

#!/usr/bin/env bash

# @(#) s1	Demonstrate driver for bash select row-col calculations

# Utility functions: print-as-echo, print-line-with-visual-space, debug.
# export PATH="/usr/local/bin:/usr/bin:/bin"
LC_ALL=C ; LANG=C ; export LC_ALL LANG
pe() { for _i;do printf "%s" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C perl

FILE=${1-data1}

pl " Results, $FILE:"
./p2 $FILE 80

FILE=data2
pl " Results, $FILE:"
./p2 $FILE 80

pl " Results, $FILE 20:"
./p2 $FILE 20

pl " Results, $FILE 80, details:"
./p2 -d $FILE 80

exit 0

$ ./s1

Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution        : Debian 5.0.8 (lenny, workstation) 
bash GNU bash 3.2.39
perl 5.10.0

-----
 Results, data1:

For data file data1, containing:
fsaaaaa
fsbbbbb
fsccccc
hrddddd
 Maximum element length = 7

 Final calculation, COLUMNS (width) = 80:
 Rows = 4
 Cols = 1

-----
 Results, data2:

For data file data2, containing:
fsaaaaa
fsbbbbb
fsccccc
hrddddd
None of the above
 Maximum element length = 17

 Final calculation, COLUMNS (width) = 80:
 Rows = 2
 Cols = 3

-----
 Results, data2 20:

For data file data2, containing:
fsaaaaa
fsbbbbb
fsccccc
hrddddd
None of the above
 Maximum element length = 17

 Final calculation, COLUMNS (width) = 20:
 Rows = 5
 Cols = 1

-----
 Results, data2 80, details:
debug: value, filename, COLUMNS = data2, 80
debug: value, array a length 5 "fsaaaaa fsbbbbb fsccccc hrddddd None of the above", longest = 17
debug: value initial cols = 4
debug: value before  , rows, cols = 2, 4
debug: value after   , rows, cols = 2, 3
debug: value adjusted, rows, cols = 2, 3

For data file data2, containing:
fsaaaaa
fsbbbbb
fsccccc
hrddddd
None of the above
 Maximum element length = 17

 Final calculation, COLUMNS (width) = 80:
 Rows = 2
 Cols = 3

#!/usr/bin/env perl

# @(#) p2	Demonstrate rows, cols calculations for bash "select".

use warnings;
use strict;

# Short circuit for debug.
# Use with d(), keys: Action, Location, Value.
our ($debug);
$debug = 0;
if ( @ARGV && $ARGV[0] =~ /-de*b*u*g*/ ) {
  $debug = 1;
  shift;
}

# Read list, calculate longest line.

my ( $filename, $COLUMNS, $f, $longest, $t1, @a, @list );
my ( $list_len, $max_elem_len, $cols, $rows, $string );

$filename = shift || "data1";
$COLUMNS  = shift || "80";
d("value, filename, COLUMNS = $filename, $COLUMNS");

open( $f, "<", $filename ) || die "Cannot open file $filename\n";

$longest = 0;
while (<$f>) {
  chomp;
  $t1 = length($_);
  $longest = $t1 > $longest ? $t1 : $longest;
  push @a, $_;
}
$list_len = scalar(@a);
d("value, array a length $list_len \"@a\", longest = $longest");
@list         = @a;
$max_elem_len = $longest;

$cols = $max_elem_len ? $COLUMNS / $max_elem_len : 1;
$cols = int($cols);
d("value initial cols = $cols");
$cols = 1 if $cols == 0;

$rows = $list_len ? $list_len / $cols + ( $list_len % $cols != 0 ) : 1;
$rows = int($rows);

d("value before  , rows, cols = $rows, $cols");
$cols = $list_len ? $list_len / $rows + ( $list_len % $rows != 0 ) : 1;
$cols = int($cols);
d("value after   , rows, cols = $rows, $cols");

if ( $rows == 1 ) {
  $rows = $cols;
  $cols = 1;
}
d("value adjusted, rows, cols = $rows, $cols");

print "\n";
print "For data file $filename, containing:\n";
foreach $string (@list) {

  print "$string\n";
}
print " Maximum element length = $max_elem_len\n";
print "\n";

print " Final calculation, COLUMNS (width) = $COLUMNS:\n";
print " Rows = $rows\n";
print " Cols = $cols\n";

exit;

sub d {

  # Debug - print strings if debug does not fail.
  if ( not $debug ) {
    return;
  }
  elsif ( scalar(@_) == 0 ) {
    print "\n";
  }
  else {
    print STDERR join "", "debug: ", @_, "\n";
  }
}