#!/usr/bin/env bash

# @(#) s1	Demonstrate perl Text::Parts for splitting file.

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() { : ; }
edges() { head -3 $1;pe "---";tail -3 $1; pe ; }
C=$HOME/bin/context && [ -f $C ] && $C

FILE=${1-data1}
pl " Edges of $(wc -l <$FILE) lines in input data file $FILE:"
# head -5 $FILE ; pe "---" ; tail -5 $FILE
edges $FILE

pl " Sample perl script to split file:"
cat p1

# Remove debris form previous runs, try various PARTS.
rm -f file*.txt
PARTS=6
PARTS=3
PARTS=10
pl " Splitting $FILE into $PARTS parts:"
./p1 $FILE $PARTS

pl " Files created:"
wc -l file*.txt

pl " Sample result, edges of part 1:"
edges file1.txt
pl " Sample result, edges of part $PARTS:"
edges file$PARTS.txt

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 GNU/Linux 5.0.8 (lenny) 
bash GNU bash 3.2.39

-----
 Edges of 80 lines in input data file data1:
1
2
3
---
78
79
80


-----
 Sample perl script to split file:
#!/usr/bin/env perl

# @(#) p1	Split file into n parts, Text::Parts.
# See:
# http://search.cpan.org/~ktat/Text-Parts-0.15/lib/Text/Parts.pm

use strict;
use warnings;
use Text::Parts;

my $file  = shift || die " Need a filename to split.\n";
my $parts = shift || "4";

my $splitter = Text::Parts->new( file => $file );

$splitter->write_files(
  'file%d.txt',
  num  => $parts,
  code => \&do_after_split
);

sub do_after_split {
  my ( $filename, $f );
  $filename = shift;    # e.g. 'path/to/name1.txt'
  open( $f, ">>", $filename ) || die "Cannot open $filename for append.\n";
  print $f "\n";
  close $f;
}

exit(0);

-----
 Splitting data1 into 10 parts:

-----
 Files created:
 11 file1.txt
  7 file10.txt
  8 file2.txt
  8 file3.txt
  8 file4.txt
  8 file5.txt
  8 file6.txt
  7 file7.txt
  8 file8.txt
  7 file9.txt
 80 total

-----
 Sample result, edges of part 1:
1
2
3
---
9
10
11


-----
 Sample result, edges of part 10:
74
75
76
---
78
79
80