Why isn't getops handling all parameters?

[Calab]

For some reason, getops is only seeing 9 parameter entries of a bash command line that has 12 parameter entries. I can't figure out why. None of the parameters have special characters and the code is very simple...

parameters = sys.argv[1:]
opts, args = getopt.getopt(parameters, "u:c:t:r:pi")

print(parameters)
print(opts)

This is the command I enter:
./myscript.py -c Param1 -t Param2 -r Param3 -u Param4 -p Param5 -i Param6

This is the output I see:

Output:
['-c', 'Param1', '-t', 'Param2', '-r', 'Param3', '-u', 'Param4', '-p', 'Param5', '-i', 'Param6']
[('-c', 'Param1'), ('-t', 'Param2'), ('-r', 'Param3'), ('-u', 'Param4'), ('-p', '')]

What I expect to see:

Output:
['-c', 'Param1', '-t', 'Param2', '-r', 'Param3', '-u', 'Param4', '-p', 'Param5', '-i', 'Param6']
[('-c', 'Param1'), ('-t', 'Param2'), ('-r', 'Param3'), ('-u', 'Param4'), ('-p', 'Param5'), ('-i', 'Param6')]

getops is seeing the -p directive, but not the value it is being passed. It completely ignores the -i directive.

I'm using Python v 3.7.11 on a RHEL 7.9 system.

[Gribouillis]

Getopt is very old-fashioned, why not use argparse, which is much more friendly and powerful?

[deanhystad]

Missing colon betweem p and i in the getopt() arguments

[Calab]

Missing colon betweem p and i in the getopt() arguments

P and I are optional directives, not required every time.

[Calab]

Getopt is very old-fashioned, why not use argparse, which is much more friendly and powerful?

Because I hadn't heard about argparse. :)

Will take a look at argparse.

Still doesn't explain the issue though.

[deanhystad]

P and I are optional directives, not required every time.

Colon indicates the option is followed by a value. It has nothing to do with the option being required or optional. Your option string "u:c:t:r:pi" tells getopt that u, c, t and r are followed by an option value, p and i are not followed by a value. When parsing your arguments, getopt sees the value after p as a potential option i, not a value for p.

import getopt
import sys

args = sys.argv[1:]
print("args", args)
print("a:b:c", getopt.getopt(sys.argv[1:], "a:b:c"))
print("a:b:c:", getopt.getopt(sys.argv[1:], "a:b:c:"))

Output:
args ['-a', 'A', '-b', 'B', '-c', 'C']
a:b:c ([('-a', 'A'), ('-b', 'B'), ('-c', '')], ['C'])
a:b:c: ([('-a', 'A'), ('-b', 'B'), ('-c', 'C')], [])

[Calab]

P and I are optional directives, not required every time.

Colon indicates the option is followed by a value. It has nothing to do with the option being required or optional. Your option string "u:c:t:r:pi" tells getopt that u, c, t and r are followed by an option value, p and i are not followed by a value. When parsing your arguments, getopt sees the value after p as a potential option i, not a value for p.

import getopt
import sys

args = sys.argv[1:]
print("args", args)
print("a:b:c", getopt.getopt(sys.argv[1:], "a:b:c"))
print("a:b:c:", getopt.getopt(sys.argv[1:], "a:b:c:"))

Output:
args ['-a', 'A', '-b', 'B', '-c', 'C']
a:b:c ([('-a', 'A'), ('-b', 'B'), ('-c', '')], ['C'])
a:b:c: ([('-a', 'A'), ('-b', 'B'), ('-c', 'C')], [])

Ohhhhhhh... Now that makes perfect sense. I misread the documentation and was thinking I was crazy.

I've switched to argparse anyhow. It is definitely more powerful.

[deanhystad]

Most of the standard library documentation is pretty good. The documentation for getopt is not.