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chapter14/chg_base_bc.bash

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+#!/bin/bash
+#
+# SCRIPT: chg_base_bc.bash
+# AUTHOR: Randy Michael
+# DATE: 10/4/2007
+# REV: 1.1.A
+#
+# PURPOSE: This script converts numbers between base
+# 2 through base 16 using the bc utility. The user 
+# is prompted for input.
+#
+# NOTE: Numbers are in the following format:
+#
+#     base#number
+#
+# EXAMPLE:  16#264bf
+#
+##########################################
+# DEFINE FILES AND VARIABLES HERE
+##########################################
+
+# Setup the correct awk usage. Solaris needs to
+# use nawk instead of awk.
+
+case $(uname) in
+SunOS) AWK="nawk"
+       ;;
+    *) AWK="awk"
+       ;;
+esac
+
+##########################################
+# BEGINNING OF MAIN
+##########################################
+
+# Prompt the user for an input number with base
+
+echo -e "\nInput the number to convert in the following format:
+
+Format: base#number
+
+Example: 16#264BF \n"
+
+read IBASE_NUM
+
+# Extract the base from the ibase_num variable
+
+IBASE=$(echo $IBASE_NUM | $AWK -F '#' '{print $1}')
+INUMBER=$(echo $IBASE_NUM | $AWK -F '#' '{print $2}')
+
+# Test to ensure the input base is between 2 and 16
+
+if (( IBASE < 2 || IBASE > 16 ))
+then
+    echo -e "\nERROR: Input base must be between 2 and 16\n"
+    exit 1
+fi
+
+# The bc utility requires all number bases greater
+# than 10 use uppercase characters for all 
+# non-numeric character numbers, i.e. hex numbers.
+# We use the tr command to upcase all lowercase
+# characters.
+
+if (( IBASE > 10 ))
+then
+    INUMBER=$(echo $INUMBER | tr '[a-z]' '[A-Z]')
+fi
+
+# Ask the user for the output base
+
+echo -e "\nWhat base do you want to convert $IBASE_NUM to?
+NOTE: base 2 through 16 are valid\n"
+echo -e "Output base: \c"
+read OBASE
+
+# Test to ensure the output base is an integer
+
+case $OBASE in
+  [0-9]*) : # do nothing
+          ;;
+       *) echo -e "\nERROR: $obase is not a valid number\n"
+          exit 1
+          ;;
+esac
+
+# Test to ensure the output base is between 2 and 16
+
+if (( OBASE < 2 || OBASE > 16 ))
+then
+    echo -e "\nERROR: Output base must be between 2 and 16\n"
+    exit 1
+fi
+
+# Save the input number before changing the base
+
+IN_BASE_NUM=$IBASE_NUM
+
+# Convert the input number to decimal
+
+DEC_EQUIV=$(echo "ibase=$IBASE; $INUMBER" | bc)
+
+# Convert the number to the desired output base
+
+RESULT=$(echo "obase=$OBASE; $DEC_EQUIV" | bc)
+
+# Display the result
+
+echo -e "\nInput number $IN_BASE_NUM is equivalent to \
+${OBASE}#${RESULT}\n"
+