Shell reads multiple files at the same time

Read two files at the same time, and merge their peers into one line to write to a merged file

Shell script:

#!/bin/bash

#set
-x CD ' dirname ' $ '/. /
inas_script_root= ' pwd '



function Make_if_no_existis_dir ()
{local

   dir=$1

   if [!-e ' ${dir} '  ]
   Then

           mkdir  -P "${dir}"
   fi return

   0

}


function Union2 ()
{local
  File_ Name1=$1 local
  file_name2=$2 local

  union_dir=${inas_script_root}/file/union

  make_if_no_existis_ Dir ${union_dir}

  >${union_dir}/union.txt


 exec 3< "${inas_script_root}/file/${file_name1}"
 EXEC 4< "${inas_script_root}/file/${file_name2}" while

 read line1<&3 && read line2<&4
 do
         echo $line 1 $line 2 >> ${union_dir}/union.txt
 done


}

Union2 $

A.txt content:

AAA
BBB
CCC
ddd
Eee
FFF

B.txt content:

AAA
BBB
CCC
DDD
EEE
FFF
GGG

Run the script

SH union_file.sh  a.txt b.txt

Get the merged file Union.txt

AAA Triple-A BBB, CCC
CCC
ddd ddd
eee Eee
FFF FFF
GGG GGG

Reference Link: https://www.cnblogs.com/tangxin-blog/p/6531812.html