json_cmd.sh

#
# Shell functions to wrap cmdline utility output with JSON
#
# Useful for running shell commands and then extracting output with logstash
#
json_kv_pair()
{
    K="$1" # key
    V="$2" # value
    Q="$3" # quote
    T="$4" # term
    echo -n " \"$K\":$Q"
    echo -n "$V" | sed -e 's/"/\\\"/g' -e ':a;N;$!ba;s/\n/\\n/g' -e 's/\t/\\t/g'
    [ -z "$T" ] && echo -n "$Q," || echo -n "$Q"
}

json_kv_int() { json_kv_pair "$1" "$2" ""  "$3"; }
json_kv_str() { json_kv_pair "$1" "$2" '"' "$3"; }

json_wrap_cmd()
{
    CMD="$1"

    echo -n "{"

    json_kv_int "timestamp_start" "$(date +%s)"
    json_kv_str "cmd" "$CMD"

    OUT=$(echo "$CMD" | sh 2>&1)
    RET=$?
    DONE=$(date +%s)
    json_kv_str "output" "$OUT"
    json_kv_int "ret" "$RET"

    json_kv_int "timestamp_stop" "$DONE" true

    # TODO break-up stderr and stdout
    echo " }"
}