ls -1 A > data1

 
#!/usr/bin/env bash

# @(#) s1       Demonstrate intersperse, shuffle of lines, gather.

# 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" "$_i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
em() { pe "$*" >&2 ; }
db() { ( printf " db, ";for _i;do printf "%s" "$_i";done;printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C gather dixf scatter

FILE=${1-data1}

pl " Input data files data*:"
head data*

pl " Results, 1 item from each list:"
gather data*

pl " Results, 2 from column A, one from B and C:"
gather data1:2 data2 data3

pl " Results, as previous, but separator is newline:"
gather -s '\n' data1:2 data2 data3

pl " Help from gather:"
gather -h

pl " Details about gather, scatter:"
dixf gather scatter

exit 0

$ ./s1
Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 3.16.0-4-amd64, x86_64
Distribution        : Debian 8.8 (jessie) 
bash GNU bash 4.3.30
gather (local) 1.1
dixf (local) 1.49
scatter (local) 1.4

-----
 Input data files data*:
==> data1 <==
1.txt
2.txt
3.txt
4.txt
5.txt

==> data2 <==
a.txt
b.txt
c.txt
d.txt
e.txt

==> data3 <==
101.txt
102.txt
103.txt
104.txt
105.txt

-----
 Results, 1 item from each list:
1.txt
a.txt
101.txt
2.txt
b.txt
102.txt
3.txt
c.txt
103.txt
4.txt
d.txt
104.txt
5.txt
e.txt
105.txt

-----
 Results, 2 from column A, one from B and C:
1.txt 2.txt
a.txt
101.txt
3.txt 4.txt
b.txt
102.txt
5.txt 103.txt
c.txt
104.txt
d.txt
105.txt
e.txt

-----
 Results, as previous, but separator is newline:
1.txt
2.txt
a.txt
101.txt
3.txt
4.txt
b.txt
102.txt
5.txt
103.txt
c.txt
104.txt
d.txt
105.txt
e.txt

-----
 Help from gather:

gather - Read, shuffle, weave, intersperse lines from multiple inputs to STDOUT.

usage: gather [options] -- [files]

options:

--separator=SEP
  Set output token separator to SEP, default " ", and "\n" is
  accepted as NEWLINE.  The SEP is used when more than one line is
  read from a file. This allows one to easily capture short lines
  into a single output line.

--help (or -h)
  print this message and quit.

[files]
  filename1:count1 filename2:count2 ... filename3:count3
  Each filenamei will be read in succession, and will be written
  to standard output, continuing until EOF on every file.


-----
 Details about gather, scatter:

gather	Read, shuffle, weave, intersperse lines from multiple input files. (what)
Path    : ~/bin/gather
Version : 1.1
Length  : 224 lines
Type    : Perl script, ASCII text executable
Shebang : #!/usr/bin/env perl
Help    : probably available with -h,--help
Modules : (for perl codes)
 strict	1.08
 warnings	1.23
 English	1.09
 Carp	1.3301
 Getopt::Long	2.42
 feature	1.36_01

scatter	Write, deal, unravel disperse lines to multiple output files. (what)
Path    : ~/bin/scatter
Version : 1.4
Length  : 190 lines
Type    : Perl script, ASCII text executable
Shebang : #!/usr/bin/env perl
Modules : (for perl codes)
 strict	1.08
 warnings	1.23
 English	1.09
 Carp	1.3301
 Data::Dumper	2.151_01
 Getopt::Long	2.42
 feature	1.36_01

$ gather <( ls -1 A ) <( ls -1 B )
1.txt
a.txt
2.txt
b.txt
3.txt
c.txt
4.txt
d.txt
5.txt
e.txt