Hal and python3.

dab77
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6 years 11 months ago - 6 years 11 months ago #150897 by dab77

Replied by dab77 on topic Hal and python3.

Unfortunately it doesn't work from python (or at least I can't..)

if doing:

Code:

rip_cmd = ('source /home/dab/linuxcnc/scripts/rip-environment')
print(subprocess.call(rip_cmd, shell=True))

import hal

i got:

Code:

/bin/sh: 1: source: not found
...

don't know why, since in the terminal 'source' is well accepted..

A workaround I used in the meantime is this:

Code:

sys.path.append('/home/dab/linuxcnc/lib/python/')
rip_cmd = '/home/dab/linuxcnc/scripts/rip-environment'

import hal

and then every hal command I need I put 'rip_cmd' before as:

Code:

halrun_U = rip_cmd + " halrun -U"
os.system(halrun_U)
..or..
launch_halcmd = rip_cmd + ' halcmd -v -f halga.hal'
os.system(launch_halcmd)

Last edit: 6 years 11 months ago by dab77.

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dgarrett
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6 years 11 months ago #150919 by dgarrett

Replied by dgarrett on topic Hal and python3.

Unfortunately it doesn't work from python

The 'source' (equivalently '.') command is a shell
(/bin/bash) *builtin*. You need to 'source' the
rip-environment script in the terminal *BEFORE*
invoking your python script in order to populate the
environmental variables needed to find LinuxCNC
executables and the modules or libraries used for its
scripting languages (python,tcl). The environmental
variables created by sourcing the rip-environment
script will then be available to child processes (eg
python scripts) of the terminal process.

Example (using /home/git/linuxcnc-dev as the root directory for a
LinuxCNC RIP build):

Code:

$ source /home/git/linuxcnc-dev/scripts/rip-environemnt
$ python 
...
>>> import os
>>> os.environ.get('PYTHONPATH')
'/home/git/linuxcnc-dev/lib/python'

Ref:
For modern Linux distributions, the default shell used
in a terminal is bash (/bin/bash)

Code:

$ man bash
...
SHELL BUILTIN COMMANDS
...
  .  filename [arguments]
  source filename [arguments]
  Read and execute commands from filename in the current shell en‐
  vironment  and  ... (much more)

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dab77
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6 years 11 months ago #150925 by dab77

Replied by dab77 on topic Hal and python3.

Ok, I should have said I'm developing in pycharm, and sourcing the rip-environment in a terminal doesn't help if then I run my code from inside pycharm.

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dgarrett
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6 years 11 months ago #150929 by dgarrett

Replied by dgarrett on topic Hal and python3.

I run my code from inside pycharm.

I don't know anything about pycharm but find it suprising
that it doesn't propagate a shell environment. Perhaps
you start pycham from a menu -- if so, you could try
starting pycharm in a terminal *after* sourcing rip-environemnt.

If that guess is unhelpful, you would need to set all the
the paths required by LinuxCNC within your python program.
You can ascertain which items are set or updated by
rip-environment by comparing the environment before and
after sourcing rip-environment. Example:

Code:

$ # new shell before sourcing rip-environment
$ env >| before.txt
$ source /home/git/linuxcnc-dev/scripts/rip-environment
$ env >| after.txt
$ diff before.txt after.txt

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Hal and python3.