Command for appending/prepending text to lines

apline

#!/bin/bash

# Append/prepend text to line

function usage
{
    echo -e "Usage: $(basename "$0") [a|p] TEXT"
    echo
    echo -n "apline reads from standard input and appends/prepends TEXT to "
    echo "each line."

    exit 1
}

[[ $# > 2 || $# -eq 0 ]] && usage

if [[ $# -eq 1 ]]
then
    ACTION="p"
    TEXT="$1"
else
    ACTION="$1"
    TEXT="$2"
fi

[[ "$ACTION" != "a" && "$ACTION" != "p" ]] && usage

INSERT=1

while IFS= read -d "" -s -N 1 CHAR
do
    [[ -n "$INSERT" && "$ACTION" == "p" ]] && printf "%s" "$TEXT"

    [[ "$CHAR" == $'\n' && "$ACTION" == "a" ]] && printf "%s" "$TEXT"

    printf "$CHAR"

    unset INSERT

    [[ "$CHAR" == $'\n' ]] && INSERT=1
done