Output JSON from Bash script

Question

So I have a bash script which outputs details on servers. The problem is that I need the output to be JSON. What is the best way to go about this? Here is the bash script:

# Get hostname
hostname=`hostname -A` 2> /dev/null

# Get distro
distro=`python -c 'import platform ; print platform.linux_distribution()[0] + " " +        platform.linux_distribution()[1]'` 2> /dev/null

# Get uptime
if [ -f "/proc/uptime" ]; then
uptime=`cat /proc/uptime`
uptime=${uptime%%.*}
seconds=$(( uptime%60 ))
minutes=$(( uptime/60%60 ))
hours=$(( uptime/60/60%24 ))
days=$(( uptime/60/60/24 ))
uptime="$days days, $hours hours, $minutes minutes, $seconds seconds"
else
uptime=""
fi

echo $hostname
echo $distro
echo $uptime

So the output I want is something like:

{"hostname":"server.domain.com", "distro":"CentOS 6.3", "uptime":"5 days, 22 hours, 1 minutes, 41 seconds"}

Thanks.

Answer 1

If you only need to output a small JSON, use printf:

printf '{"hostname":"%s","distro":"%s","uptime":"%s"}\n' "$hostname" "$distro" "$uptime"

Or if you need to produce a larger JSON, use a heredoc as explained by leandro-mora. If you use the here-doc solution, please be sure to upvote his answer:

cat <<EOF > /your/path/myjson.json
{"id" : "$my_id"}
EOF

---

Some of the more recent distros, have a file called: /etc/lsb-release or similar name (cat /etc/*release). Therefore, you could possibly do away with dependency your on Python:

distro=$(awk -F= 'END { print $2 }' /etc/lsb-release)

An aside, you should probably do away with using backticks. They're a bit old fashioned.

Answer 2

I find it much more easy to create the json using cat:

cat <<EOF > /your/path/myjson.json
{"id" : "$my_id"}
EOF

Answer 3

I'm not a bash-ninja at all, but I wrote a solution, that works perfectly for me. So, I decided to share it with community.

First of all, I created a bash script called json.sh

arr=();

while read x y; 
do 
    arr=("${arr[@]}" $x $y)
done

vars=(${arr[@]})
len=${#arr[@]}

printf "{"
for (( i=0; i<len; i+=2 ))
do
    printf "\"${vars[i]}\": ${vars[i+1]}"
    if [ $i -lt $((len-2)) ] ; then
        printf ", "
    fi
done
printf "}"
echo

And now I can easily execute it:

$ echo key1 1 key2 2 key3 3 | ./json.sh
{"key1":1, "key2":2, "key3":3}

Answer 4

@Jimilian script was very helpful for me. I changed it a bit to send data to zabbix auto discovery

arr=()

while read x y;
do
    arr=("${arr[@]}" $x $y)
done

vars=(${arr[@]})
len=${#arr[@]}

printf "{\n"
printf "\t"data":[\n"

for (( i=0; i<len; i+=2 ))
do
     printf "\t{  "{#VAL1}":\"${vars[i]}\",\t"{#VAL2}":\"${vars[i+1]}\"  }"

    if [ $i -lt $((len-2)) ] ; then
        printf ",\n"
    fi
done
printf "\n"
printf "\t]\n"
printf "}\n"
echo

Output:

    $ echo "A 1 B 2 C 3 D 4 E 5" | ./testjson.sh
{
    data:[
    {  {#VAL1}:"A", {#VAL2}:"1"  },
    {  {#VAL1}:"B", {#VAL2}:"2"  },
    {  {#VAL1}:"C", {#VAL2}:"3"  },
    {  {#VAL1}:"D", {#VAL2}:"4"  },
    {  {#VAL1}:"E", {#VAL2}:"5"  }
    ]
}

Answer 5

I wrote a tiny program in Go, json_encode. It works pretty good for such cases:

$ ./getDistro.sh | json_encode
["my.dev","Ubuntu 17.10","4 days, 2 hours, 21 minutes, 17 seconds"]

Answer 6

data=$(echo  " BUILD_NUMBER : ${BUILD_NUMBER} , BUILD_ID : ${BUILD_ID} , JOB_NAME : ${JOB_NAME} " | sed 's/ /"/g')

output => data="BUILD_NUMBER":"29","BUILD_ID":"29","JOB_NAME":"OSM_LOG_ANA"

Answer 7

To answer the subject line, if you were to needing to to get a tab separated output from any command line and needed it to be formatted as a JSON list of lists, you can do the following:

echo <tsv_string> | python3 -c "import sys,json; print(json.dumps([row.split('\t') for row in sys.stdin.read().splitlines() if True]))

For example, to get a zfs list output as json:

zfs list -Hpr -o name,creation,mountpoint,mounted | python3 -c "import sys,json; print(json.dumps([row.split('\t') for row in sys.stdin.read().splitlines() if True]))