#!/bin/bash
# Adds up a specified column (of numbers) in the target file.
ARGS=2
E_WRONGARGS=65
if [ $# -ne "$ARGS" ] # Check for proper no. of command line args.
then
echo "Usage: `basename $0` filename column-number"
exit $E_WRONGARGS
fi
filename=$1
column_number=$2
# Passing shell variables to the awk part of the script is a bit tricky.
# See the awk documentation for more details.
# A multi-line awk script is invoked by awk ' ..... '
# Begin awk script.
# -----------------------------
awk '
{ total += $'"${column_number}"'
}
END {
print total
}
' "$filename"
# -----------------------------
# End awk script.
# It may not be safe to pass shell variables to an embedded awk script,
# so Stephane Chazelas proposes the following alternative:
# ---------------------------------------
# awk -v column_number="$column_number" '
# { total += $column_number
# }
# END {
# print total
# }' "$filename"
# ---------------------------------------
exit 0
