UNIX for Dummies Questions & Answers

#!/usr/bin/env sh

# @(#) s1       Demonstrate feature.

#  ____
# /
# |   Infrastructure BEGIN

set -o nounset
echo

debug=":"
debug="echo"

## The shebang using "env" line is designed for portability. For
#  higher security, use:
#
#  #!/bin/sh -

## Use local command version for the commands in this demonstration.

echo "(Versions displayed with local utility \"version\")"
uname -rs
version >/dev/null 2>&1 && version bash join

echo

FILE1=${1-data1}
echo " Input file $FILE1:"
cat $FILE1

echo
FILE2=${1-data2}
echo " Input file $FILE2:"
cat $FILE2

# |   Infrastructure END
# \
#  ---

echo
echo " Results from processing:"
join -a 1 -e 0 $FILE1 $FILE2

exit 0

$ ./s1

(Versions displayed with local utility "version")
SunOS 5.10
GNU bash 3.00.16
join (local) - no version provided.

 Input file data1:
aaa 50
bbb 60

 Input file data2:
aaa 40

 Results from processing:
aaa 50 40
bbb 60