How to measure execution time in a shell script in Python?

Question

I created this sh script and want to measure time spent on the program:

#!/bin/bash

start=`date +%s`

cd nlu/creator
python3 move_file.py  ../../../../../base_data/   ../../resources/kb/

python3 converter.py
python3 transformer.py

cd  ../../resources/kb/
find . -name '*.xml' | xargs  -I{} rm -rf {}
find . -name '*Object.txt' | xargs  -I{} rm -rf {}

end =`date +%s`
runtime=$((end-start))

echo "Building time: ${runtime}"

I execute:

nlu/creator/builder.sh

The error message is:

nlu/creator/builder.sh: line 15: end: command not found
Building time: -1651032434

why does it complain about 'end:command not found'?

Also, why is the time a negative number? I am on a Mac.

Answer 1

why does it complain?

This is general shell script syntax:

In general, P X Y runs the command P with the two arguments X and Y. Similarily, end = something runs the command end with the two arguments = and something.

Assignment is done by VAR=VALUE, for instance

end=something

If you one day need to execute a command named end=something (i.e. not treat it as assignment, you still can do it by writing

'end=something'

BTW: If you are only interested in knowing the time and are not picky about a particular format of how the time is printed, you could also remove your timing calculation from the script completely, and run the script with the time builtin:

time nlu/creator/builder.sh

Give it a try!