Problem with ipython / readline / ncurses

[maxnoe]

I did a fresh install of anaconda3 this morning, Linux x86_64.

When i first opened ipython, no colour was present and tabcompletion did not work. Along came the error (or warning):

WARNING: Readline services not available or not loaded.
WARNING: The auto-indent feature requires the readline library

Which was not gone after i did conda install readline.

I then tried to do import readline, which caused the error

>>> import readline
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: libncursesw.so.5: cannot open shared object file: No such file or directory

After conda install ncurses ipython and readline worked again, besides one minor thing:
Ctrl + l does not clear the screen anymore, %clear works.

[maxnoe]

I think this is connected to #42
as i'm also having the problem with blessings 'could not find terminfo database'

[maxnoe]

I narrowed it down to the provided version of the ncurses lib, it does not finde the terminfo db:

blessings is broken:

In [3]: import blessings

In [4]: blessings.Terminal()
---------------------------------------------------------------------------
error                                     Traceback (most recent call last)
<ipython-input-4-c5bca101e4fa> in <module>()
----> 1 blessings.Terminal()

/home/maxnoe/.local/anaconda3/lib/python3.4/site-packages/blessings/__init__.py in __init__(self, kind, stream, force_styling)
    104             # somewhere.
    105             setupterm(kind or environ.get('TERM', 'unknown'),
--> 106                       self._init_descriptor)
    107 
    108         self.stream = stream

error: setupterm: could not find terminfo database

This works with a system ncurses 5.9 library, but arch switched to 6, this is why it stopped working.

[itoijala]

Works for me after conda install ncurses and restarting ipython.
I don't have a module blessings.

[maxnoe]

Does ctrl + l clear your screen?

Does

import curses
curses.setupterm() 

work?

[itoijala]

I should learn to read better…

[itoijala]

EDIT: this is wrong. The trace is from my working native IPython.

The terminfo db is found:
strace gives:

stat("/home/ismo/.terminfo", 0x55e304e28170) = -1 ENOENT (No such file or directory)
 5345 stat("/usr/share/terminfo", {st_mode=S_IFDIR|0755, st_size=84, ...}) = 0
 5346 access("/usr/share/terminfo/r/rxvt-unicode-256color", R_OK) = 0
 5347 open("/usr/share/terminfo/r/rxvt-unicode-256color", O_RDONLY) = 8
 5348 fstat(8, {st_mode=S_IFREG|0644, st_size=2234, ...}) = 0
 5349 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fbe3ea55000
 5350 read(8, "\32\1N\0\35\0\37\0p\1$\5rxvt-unicode-256colo"..., 4096) = 2234
 5351 read(8, "", 4096)                       = 0
 5352 close(8)                                = 0
 5353 munmap(0x7fbe3ea55000, 4096)            = 0

I guess the db is not compatible?

[maxnoe]

So the problem is, that the terminfo db is generated by ncurses6 and the provided ncurses is ncurses 5.9?

Does that mean conda has to provide its own terminfodb?

[ahmadia]

Folks, can you confirm that this is an issue tied in to having ncurses6 on your system?

[maxnoe]

Yes.

EDIT: actually no, the conda ncurses is broken. we just didn't notice before because we were using a system ncurses 5.

[itoijala]

The strace above was accidentally from my working native ipython.
Anaconda ipython does not even try to stat anything named terminfo.
Setting TERMINFO doesn't help.

[maxnoe]

Should have mentioned that, also tried to set TERMINFO.

[itoijala]

I rebuilt ncurses without --enable-termcap and it works now.
Setting TERMINFO is necessary, otherwise it looks for the files inside the anaconda tree.
This could be solved by compiling in a better default path.

1. Get the files from here: https://github.com/conda/conda-recipes/tree/master/ncurses
2. Remove --enable-termcap from build.sh
3. Get the patch for compiling with GCC 5.1: https://raw.githubusercontent.com/cloudius-systems/osv/07e2d9032dbb3f4f2b0d0133e0eccd5be05dd05d/modules/ncurses/ncurses-5.9-gcc-5.patch
4. Add it to meta.yaml
5. conda build ncurses
6. conda install -f <path output by build>
7. TERMINFO=/usr/share/terminfo ipython

EDIT: My conclusion: normally anaconda uses the system ncurses which looks for and finds terminfo. This doen't work if the system has ncurses6. The conda ncurses never looks for terminfo, only termcap.

[maxnoe]

Could you post the new meta.yaml?