dross dross - 1 year ago 89
JSON Question

Passing bash variable to python command within a shell script

Needing to extract two variables per line from a JSON file and use each of these 2 variables in separate follow up commands.

My script is so far:



old_IFS=$IFS # save the field separator
IFS=$'\n' # new field separator, the end of line

for line in $(cat $VCTRL_OUT)
python -c 'import json,sys;obj=json.load($line);print obj["ip_range"]'

The second to last line is wrong and need to know how to do this.

The following works:

cat /tmp/workingfile.json | head -n +1 | python -c 'import json,sys;obj=json.load(sys.stdin);print obj["ip_range"]';

But not sure how to do the same in the bash script for loop.

Answer Source

Python wouldn't be my first choice for this kind of one-liner, but you might try



parse_json () {
    python -c $'import json,fileinput\nfor line in fileinput.input(): print json.loads(line)["ip_range"]' "$1"
while IFS= read -r ip_range; do
   # do your thing with ip_range
done < <(parse_json "$VCTRL_OUT")

One alternative is to replace the Python bit with jq:

while IFS= read -r ip_range; do
  # ...
done < <( jq -rR 'fromjson | .ip_range' "$VCTRL_OUT")

Another alternative is to replace the entire bash script with Python, although that may be easier said than done, depending on what the bash script is actually doing.

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