I ran into a problem when using Biopython (although it appears to be
totally unrelated to that package): writing a sequence to
sys.stdout with standard output redirected to a file caused a
shell escape sequence (\E[?1034h) to appear at the beginning of
the resulting file, thus preventing direct use of that file in other
programs.
The problem is dependent on the TERM environment variable
being set to xterm; unsetting that variable, or setting it to any
other value, makes the escape sequence disappear from Python’s output.
Looking into the terminfo database entry for xterm
revealed the following:
$ infocmp xterm | grep 1034h
smir=\E[4h, smkx=\E[?1h\E=, smm=\E?1034h, smso=\E[7m,
So the smm capability (Meta mode ON) seems to be the
cause of the trouble. I have no idea of what this capability does (well, it
turns a “meta mode” on, obviously, but I didn’t bother to search what this
meta mode could be), but I will simply remove it from the terminfo entry (I’ll
concede that’s quite an ugly “fix”, but I find it nicer than just unsetting
TERM completely, as I have seen on some forums).
$ infocmp xterm | sed 's/, smm=[^,]\+//' > xterm $ tic xterm "xterm", line 2, terminal 'xterm': meta_off but no meta_on
tic(1) complains about the Meta mode OFF capability
(rmm) being used without its counterpart, but apart from that, it
works OK, and the escape sequence does not appear anymore.