What is the chain of apps involved in process of opening a file from a file manager?

Consider these two moments, say it's Xfce 4 and a simple plain text file set up to open in Mousepad:

  1. I hit double-click the file in Thunar or Nautilus etc.,

  2. Mousepad is launched with the file

The background is that I have a bug which seems to happen even when I use different file manager as well as application. For example, Nautilus/Mousepad or Thunar/Libreoffice Calc scenarios suffer from this bug as well.

It's Debian Jessie amd64, FTM.

  • 1
    Could you clarify a little? What is this bug? What do you mean by using a "different app for A as well as Z"? Do you mean a bug when you double click in any file manager and open a file in the associated program? – terdon Nov 12 '13 at 23:54
  • @terdon Yes, I mean double-click in a FM. I have clarified the Q as well as removed the A and Z, thanks for feedback. – Alois Mahdal Nov 13 '13 at 0:44
  • For @terdon and other curious people, the bug: having utf8 as default, when you open a non-utf8 text file in Mousepad such that causes a Unicode error, MP opens a dialog asking you to select proper encoding. Now the bug is that not resolving (cancel / choose encoding) the dialog in ~30s, causes the same file be opened again, resulting in 2 such dialogs (but not 3, etc. by extended waiting---it stops at 2). I can't be sure it's MP since part of observed details happen with Calc as well. – Alois Mahdal Nov 13 '13 at 23:25

You can find out what's going on behind the scenes of an application by using the tool strace. Simply invoke the tool in question like so:

 $ strace <app>

Be warned there will be a lot of output generated by this tool so you'll likely want to dump it to a file.

 $ strace -o <logfile> <app>


First collect the log.

$ strace -o trace.log thunar

Once it either crashes or you close it, you can review the logs. Here's a dump of what the log file looks like.

$ less trace.log
execve("/usr/bin/thunar", ["thunar"], [/* 93 vars */]) = 0
brk(0)                                  = 0x13aa000
mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f7913726000
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
open("/etc/ld.so.cache", O_RDONLY)      = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=243371, ...}) = 0
mmap(NULL, 243371, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f79136ea000
close(3)                                = 0
open("/usr/lib64/libX11.so.6", O_RDONLY) = 3
read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0 \337\241\3514\0\0\0"..., 832) = 832
fstat(3, {st_mode=S_IFREG|0755, st_size=1308808, ...}) = 0
mmap(0x34e9a00000, 3403160, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x34e9a00000


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