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#!/bin/bash
# Another version of the "column totaler" script
#+ that adds up a specified column (of numbers) in the target file.
# This one uses indirect references.
ARGS=2
E_WRONGARGS=85
if [ $# -ne "$ARGS" ] # Check for proper number of command-line args.
then
echo "Usage: `basename $0` filename column-number"
exit $E_WRONGARGS
fi
filename=$1 # Name of file to operate on.
column_number=$2 # Which column to total up.
#===== Same as original script, up to this point =====#
# A multi-line awk script is invoked by
# awk "
# ...
# ...
# ...
# "
# Begin awk script.
# -------------------------------------------------
awk "
{ total += \$${column_number} # Indirect reference
}
END {
print total
}
" "$filename"
# Note that awk doesn't need an eval preceding \$$.
# -------------------------------------------------
# End awk script.
# Indirect variable reference avoids the hassles
#+ of referencing a shell variable within the embedded awk script.
# Thanks, Stephane Chazelas.
exit $?
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