I don't know what more I can find out about it before posting a question...

@Zanna Well, we could continue examining the source code.

yes, but I don't understand it :(

I think I do understand what the code is doing but I still don't know why this is happening.

Are there debug symbol packages for sed in Ubuntu?

uh...

sed-dbgsym/artful 4.4-1 amd64
  debug symbols for package sed

how do I use this thing?

@Zanna I don't have that!

Is that dbgsym package new as of 17.10, or am I missing some dbgsym repositories?

$ apt policy sed-dbgsym
sed-dbgsym:
  Installed: 4.4-1
  Candidate: 4.4-1
  Version table:
 *** 4.4-1 500
        500 ddebs.ubuntu.com artful/main amd64 Packages
        100 /var/lib/dpkg/status

ek@Io:/etc/apt/sources.list.d$ cat ddebs.list
deb ddebs.ubuntu.com xenial main restricted universe multiverse
deb ddebs.ubuntu.com xenial-updates main restricted universe multiverse
deb ddebs.ubuntu.com xenial-proposed main restricted universe multiverse

hmm... maybe it's new

surprising though...

@Zanna You run sed with a debugger, attach a debugger to a running instance of sed, or open a core dump of a (usually previous) run of sed in a debugger.

(gdb) run 'cx\y' <<<.
Starting program: /bin/sed 'cx\y' <<<.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
xy
[Inferior 1 (process 18737) exited normally]
(gdb) run 'cx\y\' <<<.
Starting program: /bin/sed 'cx\y\' <<<.
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
x\y
[Inferior 1 (process 18743) exited normally]

That doesn't give any useful information beyond running it from a shell, of course. But you can create breakpoints, step through, etc. The debug symbols usually facilitate that; it's not possible without them.

I don't know how to do anything

AMD FX-6300 plus mobo for $50

Good deal or pass?

I will put a gtx 760 plus 16gb of ram with it

I would buy it for that price just to have it around in case I needed another mobo.

Well I want to make another pc

And that is what is around me