How to set program name in Python? ($0 in Perl)

[Swaroop C H]

Hi,

Is there a way to set the program name in Python, similar to $0 in
Perl?

From `man perlvar`:

$0 Contains the name of the program being executed. On some oper-
ating systems assigning to "$0" modifies the argument
area that
the ps program sees. This is more useful as a way of
indicat-
ing the current program state than it is for hiding the
program
you're running. (Mnemonic: same as sh and ksh.)



Thanks!
Swaroop
www.swaroopch.info

 

[Steve Holden]

Hi,

Is there a way to set the program name in Python, similar to $0 in
Perl?


$0 Contains the name of the program being executed. On some oper-
ating systems assigning to "$0" modifies the argument
area that
the ps program sees. This is more useful as a way of
indicat-
ing the current program state than it is for hiding the
program
you're running. (Mnemonic: same as sh and ksh.)



Thanks!
Swaroop
www.swaroopch.info

import sys
print sys.argv[0]

regards
Steve

 

[Fredrik Lundh]

import sys
print sys.argv[0]

that *gets* the name, but assigning to sys.argv[0] doesn't *set* it (afaik).

setting the name involves overwriting the C level argv array, several large
buckets of worms, and huge portability issues, and is thus better left to non-
standard extensions.

</F>

 

[Steve Holden]

Steve Holden wrote:

Is there a way to set the program name in Python, similar to $0 in
Perl?

From `man perlvar`:

$0 Contains the name of the program being executed. On some oper-
ating systems assigning to "$0" modifies the argument
area that
the ps program sees. This is more useful as a way of
indicat-
ing the current program state than it is for hiding the
program
you're running. (Mnemonic: same as sh and ksh.)

import sys
print sys.argv[0]

that *gets* the name, but assigning to sys.argv[0] doesn't *set* it (afaik).

setting the name involves overwriting the C level argv array, several large
buckets of worms, and huge portability issues, and is thus better left to non-
standard extensions.

Indeed. My bad.

regards
Steve

 

[Swaroop C H]

Thanks Fredrik for the info.

It was not a must-have, I was just curious if it was possible.

Thanks,
Swaroop
www.SwaroopCH.info

 

[Fredrik Lundh]

Thanks Fredrik for the info.

It was not a must-have, I was just curious if it was possible.

it should be noted that some systems have a setproctitle() function, but the design
of that API comes with its own can of quality worms:

http://www.cert.org/advisories/CA-2000-13.html

</F>

 

[Bengt Richter]

import sys
print sys.argv[0]

that *gets* the name, but assigning to sys.argv[0] doesn't *set* it (afaik).

setting the name involves overwriting the C level argv array, several large
buckets of worms, and huge portability issues, and is thus better left to non-
standard extensions.

OTOH, if the intent is just to set a value for subsequent getting by way of
sys.argv[0], isn't sys.argv an ordinary list?

>>> import sys
>>> sys.argv[0] ''
>>> sys.argv[0] = '<interactive>'
>>> sys.argv[0]

>>> type(sys.argv)

<type 'list'>

Regards,
Bengt Richter

 

[Fredrik Lundh]

OTOH, if the intent is just to set a value for subsequent getting by way of
sys.argv[0], isn't sys.argv an ordinary list?

import sys
sys.argv[0] ''
sys.argv[0] = '<interactive>'
sys.argv[0]

type(sys.argv)

<type 'list'>

given that Swaroop has written a nice book about Python, I somehow
suspect that he knows how sys.argv works:

http://tinyurl.com/9s7bz

or are you saying that "ps" looks inside sys.argv on your machine?

</F>

 

[Bengt Richter]

OTOH, if the intent is just to set a value for subsequent getting by way of
sys.argv[0], isn't sys.argv an ordinary list?

import sys
sys.argv[0] ''
sys.argv[0] = '<interactive>'
sys.argv[0]

type(sys.argv)

<type 'list'>

given that Swaroop has written a nice book about Python, I somehow
suspect that he knows how sys.argv works:

http://tinyurl.com/9s7bz

Sorry, I wasn't familiar with that (or Swaroop ;-)

or are you saying that "ps" looks inside sys.argv on your machine?

Nope. Hm, I wrote a little C a few years ago utility that prints a date-time prefix
and the raw command line string but skipping arg 0. It uses win32's GetCommandLine,
which returns a string pointer.

[18:58] C:\pywk\clp>logline arg1 arg2 note preserved spaces.
20051110 18:58:24 arg1 arg2 note preserved spaces.

Maybe ctypes could be used to get the pointer and carefully poke in a mod. But I don't know if
the cmd line string is within a static fixed size array so you could lengthen it, or what.
Or have they opened the source for that? Anyway, I don't know if that is where ps (pstat on my NT box)
looks. Not handy to experiment ATM ;-)

Regards,
Bengt Richter

 

[jmdeschamps]

This is not directly what the OP wanted in regards to Perl, but to see
what one could do if one needed to change the name of the running
program, I wrote this:
## START PROGRAM
import sys
import os.path
import shutil
import os

def testChangingName(appname):
hopedfornameis = appname
mylongnameis = sys.argv[0]
mynameis = os.path.basename(mylongnameis)
basenameis = os.path.dirname(mylongnameis)
if mynameis != hopedfornameis:
shutil.copyfile(mynameis, basenameis+"/"+hopedfornameis)

os.spawnv(os.P_NOWAIT,"c:/python23/python.exe",('c:/python23/python.exe',hopedfornameis))
sys.exit()

if __name__ == "__main__":
print sys.argv[0]
testChangingName("testNameIsChanged.py")
s=raw_input("All's well!")
s=raw_input("Now do something useful")

## END PROGRAM

Since I don't know the circumstance in which the OP wanted to change
the name, I really don't know what caveats one should look out for
here.
I would be curious to know when such a function could come in handy.

Jean-Marc