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You will find on this page some useful, but unsorted, python tips and tricks that can't fit in a section of the main JYP's recommended steps for learning python page
>>> os.environ['TMPDIR'] '/data/jypmce/climafcache' >>> os.environ.get('SCRATCHDIR', '/data/jypmce/some_scratch_stuff') '/data/jypmce/some_scratch_stuff' >>> os.environ['temporary_env_var_for_THIS_script'] = 'some value' >>> os.environ['temporary_env_var_for_THIS_script'] 'some value'
This will stop the script, unless it is called in a function, and the code calling the function explicitely catches and deals with errors
raise RuntimeError('\n\nOMG! An error! :-(\nAborting script...')
A user can use CTRL-C
or kill
to stop a script, or CTRL-Z
to suspend it temporarily (use fg
to resume a suspended script). The code below can be used by the script itself to interrupt its execution, instead of raising an error
sys.exit('Some optional message about why we are stopping')
>>> os.access('/', os.W_OK) False >>> os.access('/home/jypmce/.bashrc', os.W_OK) True
The name of a script, the number of arguments (including the name of the script), and the arguments (as strings) can be accessed through the sys.argv
strings' list
Simple argv_test.py
test script:
#!/usr/bin/env python import sys nb_args = len(sys.argv) print('Number of script arguments (including script name) =', nb_args) for idx, val in enumerate(sys.argv): print(idx, val)
$ python argv_test.py Number of script arguments (including script name) = 1 0 argv_test.py $ python argv_test.py tas tas_tes.nc Number of script arguments (including script name) = 3 0 argv_test.py 1 tas 2 tas_tes.nc
Use getopt (C-style parser for command line options)
optparse (parser for command line options) is deprecated since Python version 3.2! You should now use argparse (check Upgrading optparse code for converting from optparse
to argparse
)
argparse (parser for command-line options, arguments and sub-commands) is available since Python version 3.2
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