Question

I have a python script called mythicalPythonBindings.py. It outputs something like

Establishing database connection
chanid = 1952
starttime = 2010-09-29 08:12:00
endtime = 2010-09-29 08:30:00
basename = 1952_20100929081200.mpg
stars = 0.0

I need to read this information into variables of the same name in a bash script. My bash script looks like this

#! /bin/bash

/usr/local/bin/mythicalPythonBindings.py --filename='1952_20100929081200.mpg' --DBHostName='192.168.1.110' --DBName='mythconverg' --DBUserName='mythtv' --DBPassword='mythtv' --output=./ReturnFile.txt --display|
   while read line
     do 
     case "$line" in
         "basename = "* ) 
              echo $line
              basename=`echo "$line" |sed s/'basename = '//g`
              echo $basename
         ;;
     esac
   done
echo $basename
#doing more stuff 

The problem is that when setting variables inside the piped output from mythicalPythonBindings.py, it does not export the variables. The statement “echo $basename”(inside the piped output) works, but the seccond “echo $basename”(outside the piped output) does not work.

How can I set these variables for use in the rest of the script?

edit: I need this variable to be used in other commands without saving the data to a file which must be deleted later.

Answer 1

The while loop creates a subshell when something is piped into it. To avoid that you can redirect process substitution into the done:

pythonfunc () {
    /usr/local/bin/mythicalPythonBindings.py --filename='1952_20100929081200.mpg' --DBHostName='192.168.1.110' --DBName='mythconverg' --DBUserName='mythtv' --DBPassword='mythtv' --output=./ReturnFile.txt --display
}

while ...
do
    ...
done < <(pythonfunc)
echo $basename

I would use

read var equals value
# do some validation
declare $var=$value

Using declare in this way allows you to avoid using eval.