Emacs tramp mode - filename auto complete doesn't work

Question

I am using tramp mode in Emacs to edit files over ssh. But the problem is that on remote shell I have aliased ls as "ls --color". Tramp uses ls for auto completion and it is unable to parse color coded ls output.

The solution mentioned in https://www.gnu.org/software/tramp/#Frequently-Asked-Questions is to disable coloring of output from ls by removing the alias. I do not want to do it as it is a major feature for me.

Is there are way to redefine how tramp issues ls command so that I can keep my shell configuration and still use file name completion with tramp.

Edit 1: It seems that problem is something else. I tried changing alias to 'ls --color=auto' as suggested by @chepner and then to simply 'ls'. It still doesn't work. How can I further troubleshoot the problem?

Answer 1

Tramp send following Perl snippet to get file completions

\perl5 -e 'sub case {
 my $str = shift;
 if ($ARGV[2]) {
  return lc($str);
 }
 else {
  return $str;
 }
}
opendir(d, $ARGV[0]) || die("$ARGV[0]: $!\nfail\n");
@files = readdir(d); closedir(d);
foreach $f (@files) {
 if (case(substr($f, 0, length($ARGV[1]))) eq case($ARGV[1])) {
  if (-d "$ARGV[0]/$f") {
   print "$f/\n";
  }
  else {
   print "$f\n";
  }
 }
}
print "ok\n"
' /home/ '' 0

perl5 was broken on remote host because of missing library. The solution was to manually fix the broken perl5. All this thanks to Michael Albinus.

Answer 2

Redefine your alias to read

alias ls="ls --color=auto"

This way, ls only colorizes its output when it senses it is writing to the terminal. I'm not familiar with tramp, but this should be sufficient.

Answer 3

The other thing I would do, is look in my environment if there is anything that indicates you're in "tramp mode"

Say, do:

printenv | sort > ~/notramp.txt

then in emacs/tramp-mode:

printenv | sort > ~/withtramp.txt

Diff the two env files, and see what's different.

Then, in your ~/.bashrc, you can put

if [ -z "$TRAMPFLAG" ]
then
    alias ls='ls --color=auto'
fi

Answer 4

Tramp uses sophisticated techniques to be portable across a variety of systems, but it is not foolproof. Often to provide things like remote filename completion tramp will actually run modest perl scripts on the remote host. So check to make sure you have perl 5 installed, configured, and available on the remote host.