CODEWITHSUNDEEP
pythonbashshellsubprocess
arsenal
arsenal

Reputation: 24154

How to convert shell script in one line and execute it from Python subprocess?

I have my below simple shell script which I am trying to convert in one single line so that I can execute it from my Python program using subprocess - 

#!/bin/bash
set -e

COUNT=60   #number of 10 second timeouts in 10 minutes
SUM_SYNCS=0
SUM_SYNCS_BEHIND=0
HOSTNAME=$hostname

echo $HOSTNAME

while [[ $COUNT -ge "0" ]]; do

#send the request, put response in variable
DATA=$(wget -O - -q -t 1 http://$HOSTNAME:8080/beat)

#grep $DATA for syncs and syncs_behind
SYNCS=$(echo $DATA | grep -oE 'num_syncs: [0-9]+' | awk '{print $2}')
SYNCS_BEHIND=$(echo $DATA | grep -oE 'num_syncs_behind: [0-9]+' | awk '{print $2}')

echo $SYNCS
echo $SYNCS_BEHIND

#verify conditionals
if [[ $SYNCS -gt "8" && $SYNCS_BEHIND -eq "0" ]]; then exit 0; fi

#decrement the counter
let COUNT-=1

#wait another 10 seconds
sleep 10

done

I converted the above script in one line like this - 

jsonStr = {"script": "#!/bin/bash\nset -e\n\nCOUNT=60   #number of 10 second timeouts in 10 minutes\nSUM_SYNCS=0\nSUM_SYNCS_BEHIND=0\nHOSTNAME=$hostname\t\n\necho $HOSTNAME\n\nwhile [[ $COUNT -ge \"0\" ]]; do\n\n#send the request, put response in variable\nDATA=$(wget -O - -q -t 1 http://$HOSTNAME:8080/beat)\n\n#grep $DATA for syncs and syncs_behind\nSYNCS=$(echo $DATA | grep -oE 'num_syncs: [0-9]+' | awk '{print $2}')\nSYNCS_BEHIND=$(echo $DATA | grep -oE 'num_syncs_behind: [0-9]+' | awk '{print $2}')\n\necho $SYNCS\necho $SYNCS_BEHIND\n\n#verify conditionals\nif [[ $SYNCS -gt \"8\" && $SYNCS_BEHIND -eq \"0\" ]]; then exit 0; fi\n\n#decrement the counter\nlet COUNT-=1\n\n#wait another 10 seconds\nsleep 10\n\ndone\n"}

And I am trying to execute this using Python subprocess but everytime I am getting an error - 

  File "C:\Python27\lib\json\__init__.py", line 326, in loads
    return _default_decoder.decode(s)
  File "C:\Python27\lib\json\decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
TypeError: expected string or buffer

Below is my full Python code which I am trying out - 

jsonStr = {"script": "#!/bin/bash\nset -e\n\nCOUNT=60   #number of 10 second timeouts in 10 minutes\nSUM_SYNCS=0\nSUM_SYNCS_BEHIND=0\nHOSTNAME=$hostname\t#\n\necho $HOSTNAME\n\nwhile [[ $COUNT -ge \"0\" ]]; do\n\n#send the request, put response in variable\nDATA=$(wget -O - -q -t 1 http://$HOSTNAME:8080/beat)\n\n#grep $DATA for syncs and syncs_behind\nSYNCS=$(echo $DATA | grep -oE 'num_syncs: [0-9]+' | awk '{print $2}')\nSYNCS_BEHIND=$(echo $DATA | grep -oE 'num_syncs_behind: [0-9]+' | awk '{print $2}')\n\necho $SYNCS\necho $SYNCS_BEHIND\n\n#verify conditionals\nif [[ $SYNCS -gt \"8\" && $SYNCS_BEHIND -eq \"0\" ]]; then exit 0; fi\n\n#decrement the counter\nlet COUNT-=1\n\n#wait another 10 seconds\nsleep 10\n\ndone\n"}

j = json.loads(jsonStr)

print "start"
proc = subprocess.Popen(j['script'], shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE, executable='/bin/bash')
(stdout, stderr) = proc.communicate()
print stdout
print stderr
print "end"

What is wrong in my shell script which I have converted in one line? Any thoughts?

NOTE: All my other shell scripts are working which are also in one liner from the same Python subprocess call, only this is having some problem.

Upvotes: 2

Views: 1405

Answers (1)

Aamir Rind
Aamir Rind

Reputation: 39659

The error you are getting is from json.loads(jsonStr). json.loads require a str or unicode not a dict. jsonStr is already a dict you don't need json.loads

Upvotes: 2

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