Install script fails on Ubuntu 18.04

[fishcasa]

FYI,
After a clean install of Ubuntu 18.04, the install script

~$ sudo -v && wget -nv -O- https://download.calibre-ebook.com/linux-installer.py | sudo python -c "import sys; main=lambda:sys.stderr.write('Download failed\n'); exec(sys.stdin.read()); main()"

failed with

sudo: python: command not found
Cannot write to ‘-’ (Success).

after changing

python

to

python3

in the install command, it worked.

[gbm]

Originally Posted by fishcasa

FYI,
After a clean install of Ubuntu 18.04, the install script

~$ sudo -v && wget -nv -O- https://download.calibre-ebook.com/linux-installer.py | sudo python -c "import sys; main=lambda:sys.stderr.write('Download failed\n'); exec(sys.stdin.read()); main()"

failed with

sudo: python: command not found
Cannot write to ‘-’ (Success).

after changing

python

to

python3

in the install command, it worked.

ReleaseNotes for Ubuntu 18.04

Python 2 is no longer installed by default. Python 3 has been updated to 3.6. This is the last LTS release to include Python 2 in main.

So according to this the next Ubuntu LTS will not have Python 2 in the repository.


bernie

[kovidgoyal]

The installer works fine with either python2 or python3. If Ubuntu is really releasing with no /usr/bin/python that is a bug in Ubuntu. They should have a python symlinked to python3 by default if they want to make python3 the default python. Otherwise there is no way to run scripts (like the installer) that are compatible with both python2 and python3.

Quoting https://www.python.org/dev/peps/pep-0394/

One exception to this is scripts that are deliberately written to be source compatible with both Python 2.x and 3.x. Such scripts may continue to use python on their shebang line without affecting their portability.

Of course given how generally broken packages in Ubuntu are, chances are they wont fix this, so I will have to figure out some workaround specially for them. The number of Ubuntu specific workarounds in calibre is not funny.

[kovidgoyal]

I've updated the install command to use a wrapper script that embeds the installer and launches it with the appropriate python after searching the system. Sigh.

Note that the old install command also continues to work, the same as before.

[eschwartz]

Wow, this is just... precious. (Noticed when I saw https://github.com/kovidgoyal/calibr...ad5f0d79f8bba2 show up, really made my day BTW. )

I hate to burst your bubble again, by the way... but Debian, and therefore Ubuntu, provides at least one officially supported /bin/sh implementation whose sole reason for existing is to provide the strictly POSIX-only functionality required for the most minimal shell ever. And... Debian being Debian, their policies specify POSIX SUSv3 (2004) as the target conformity thingy... which means this debian-specific shell does not support `command -v` as per HERE.

(Let's leave aside the issue of their running to SUSv3 spec, while at the same time claiming the local keyword is so important as to merit special exceptions... then also claiming they desperately need echo -n even though printf is already mandated by POSIX.)

(Why do I know this? I once made the stupid mistake of trying to improve Debian code: https://bugs.debian.org/cgi-bin/bugr...cgi?bug=889676)

Yes, they're freaking insane. But this script is meant to workaround Debian/Ubuntu bugs... so all things considered I would seriously recommend instructing people to run this script using GNU bash just in case. Or simply trying to find the location of a python3 binary to workaround not having a python one will fail for the poor souls who installed posh as their Policy-compliant Ordinary SHell.

You could, of course, try to rely on the "which" binary which is not guaranteed to exist anywhere (Debian has it as essential, Arch has it in base but people keep removing it anyway). Or just hardcode the possibilities in /usr/bin/
But I think it makes more sense to just assume a decent shell like bash, which really should be on any Linux system without exception.

Well, so much for universal scripting languages on Linux. Turns out you always need GNU bash in the end.

...

Minor errata:

$PYTHON -c "stuff; script_launch()" "$1" "$2" "$3" "$4" "$5" "$6" "$7" "$8" <<'HEREDOC'

Could be replaced by:

$PYTHON -c "stuff; script_launch()" "$@" <<'HEREDOC'

Simpler, more readable, works even in POSIX (both the decade-old Debian standard and the 5-year-old standard they vaguely intend to upgrade to, probably by the year 2030), arguably offers more future-proofing. Silently dropping additional args should be done in one place, inside the wrapped python script.

[kovidgoyal]

I dislike the terrible habit people have of hardcoding bash everywhere. Let's see if there are actually any poor souls out there that use posh as /bin/sh and also want to install calibre. If so I can probably just re-implement command -v using IFS in the script.

[eschwartz]

Fair enough. At least you'll know exactly what the issue is now, if it ever does come up.

[kovidgoyal]

Just for giggles, here it is with no command -v

https://github.com/kovidgoyal/calibr...b04f11c4781ac8

[Divingduck]

nice

[eschwartz]

I'm not convinced of the *necessity* of avoiding GNU bash, but that is certainly one way to do it. Now what are the odds that Ubuntu people will take notice of people resorting to these workarounds... none, of course!