Advanced Bash−Scripting Guide

The 0 − 255 range for function return values is a severe limitation. Global variables and other
workarounds are often problematic. An alternative method for a function to communicate a value
back to the main body of the script is to have the function write to stdout the "return value", and
assign this to a variable.
Example 34−10. Return value trickery
Advanced Bash−Scripting Guide
#!/bin/bash
# multiplication.sh
multiply ()
# Multiplies params passed.
{ # Will accept a variable number of args.
local product=1
until [ −z "$1" ]
do
let "product *= $1"
shift
done
# Until uses up arguments passed...
echo $product
# Will not echo to stdout,
} #+ since this will be assigned to a variable.
mult1=15383; mult2=25211
val1=`multiply $mult1 $mult2`
echo "$mult1 X $mult2 = $val1"
# 387820813
mult1=25; mult2=5; mult3=20
val2=`multiply $mult1 $mult2 $mult3`
echo "$mult1 X $mult2 X $mult3 = $val2"
# 2500
mult1=188; mult2=37; mult3=25; mult4=47
val3=`multiply $mult1 $mult2 $mult3 $mult4`
echo "$mult1 X $mult2 X $mult3 X mult4 = $val3"
# 8173300
exit 0
The same technique also works for alphanumeric strings. This means that a function can "return" a
non−numeric value.
capitalize_ichar ()
# Capitalizes initial character
{ #+ of argument string(s) passed.
string0="$@"
firstchar=${string0:0:1}
string1=${string0:1}
# Accepts multiple arguments.
# First character.
# Rest of string(s).
FirstChar=`echo "$firstchar" | tr a−z A−Z`
# Capitalize first character.
echo "$FirstChar$string1" # Output to stdout.
}
Chapter 34. Miscellany 350