从Bash调用的Python脚本无能为力

Question

I have a weird problem. I am calling a python script within a shell script like this:

---filename: dl.sh---
#/bin/bash
...
metaData=`python /var/www/music/getMetaData.py "$artist" "$title" | tail -n 1`
...

It is a python script that reads metadata from a json resource. In most cases it is working as desired, filling the variable metaData.

For some cases it simply returns nothing. Even print commands from the python scripts are not being called. It seems to me that the python script simply does not get executed, because when I run the command manually it always works:

python /var/www/music/getMetaData.py "Artist Name" "Title Name" | tail -n 1

In the cases the script return nothing manually executing

echo $metaData

results in a empty line.

The first lines of the python script are:

---filename: getMetaData.py---
import urllib2
import sys
import re
import datetime

print "Testing Output ..."

Not even "Testing Output ..." gets printed in these cases...

Answer 1

Try to change tail to head -1 and see if it starts working. If the last line of the script output is a blank then that is what your overall command (including tail ) would return.

Answer 2

The problem was in the passed args... Somehow spaces screw up the call to the python script.

Before:

metaData=`python /var/www/music/getMetaData.py "$artist" "$title" | tail -n 1`

Now:

artist=${artist//[ ]/;}
title=${title//[ ]/;}
metaData=`python /var/www/music/getMetaData.py "$artist" "$title" | tail -n 1`

With replacing the spaces with + it works now like a charm! Thx everybody!