Ubuntu Manpage: reptyr - Reparent a running program to a new terminal

NAME

       reptyr - Reparent a running program to a new terminal

SYNOPSIS

       reptyr PID

       reptyr -l|-L [COMMAND [ARGS]]

DESCRIPTION

       reptyr  is  a  utility  for  taking  an existing running program and attaching it to a new
       terminal. Started a long-running process over ssh, but have to leave  and  don't  want  to
       interrupt  it?  Just  start a screen, use reptyr to grab it, and then kill the ssh session
       and head on home.

       reptyr works by attaching to the target program using ptrace(2), redirecting relevant file
       descriptors,  and changing the program's controlling terminal (See tty(4)) It is this last
       detail that makes reptyr work much better than alternatives such as retty(1).

       After attaching a program, the program will appear to be either backgrounded or  suspended
       to the shell it was launched from (depending on the shell). For maximal safety you can run

              bg; disown

       in  the  old  shell to remove the association with the program, but reptyr will attempt to
       ensure that the target program remains running even if you close the shell  without  doing
       so.

OPTIONS

-T

Use an alternate mode of attaching, "TTY-stealing". In this mode, reptyr will not
ptrace(2) the target process, but will attempt to discover the terminal emulator
for that process' pty, and steal the master end of the pty. This mode is more
reliable and flexible in many circumstances (for instance, it can attach all
processes on a tty, rather than just a single process). However, as a downside,
children of sshd(8) cannot be attached via -T unless reptyr is run as root. See
⟨https://blog.nelhage.com/2014/08/new-reptyr-feature-tty-stealing/⟩ for more
information about tty-stealing.

-l, -L [COMMAND [ARGS]]

Instead of attaching to a new process, create a new pty pair, proxy the master end
to the current terminal, and then print the name of the slave pty. This can be
passed to e.g. gdb´s set inferior-tty option.

If an optional COMMAND and ARGS are passed in conjunction with -l, that command
will be executed as a child of reptyr with the REPTYR_PTY environment variable set
to the name of the slave pty. If -L is used instead of -l, then fds 0-2 of the
child will also be redirected to point to the slave, and the child will be run in a
fresh session with the slave as its controlling terminal.

-s

By default, reptyr will move any file descriptors in the target that were connected
to the target's controlling terminal to point to the new terminal. The -s option
will cause reptyr to unconditionally attach file descriptors 0, 1, and 2 in the
target, even if the target has no controlling terminal or they are not connected to
a terminal.

-v

Print the version of reptyr and exit.

-h

Print a usage message and exit.

-V

Print verbose debug output while running.

NOTES

       reptyr depends on the ptrace(2) system call to attach to the  remote  program.  On  Ubuntu
       Maverick  and  higher,  this  ability is disabled by default for security reasons. You can
       enable it temporarily by doing

               # echo 0 > /proc/sys/kernel/yama/ptrace_scope

       as root, or permanently by  editing  the  file  /etc/sysctl.d/10-ptrace.conf,  which  also
       contains more information about this setting.

BUGS

       When  attaching to some curses programs, they will not redraw the screen right away, and a
       ^L or similar will be needed to force a redraw.

       Similarly, after attaching to certain programs, the old terminal will be left  in  an  odd
       state, and a clear or even reset may be required before the old terminal is usable again.

       Attaching  to  rtorrent  (and probably some other apps) doesn't work right (rtorrent stops
       accepting input) (The problem is that rtorrent is using epoll to poll stdin, and we  don't
       update the internal reference that the epoll fd has to the old tty).

       Attaching to a process with children doesn't work right. This should be possible to fix --
       I just need to ptrace each child individually and do the same games to it.

       Attaching a less(1) process doesn't work if you have a .lessfilter file,  as  less  leaves
       around a zombie child in this case. This could be worked around.

       Bugs should be reported to the author (see below) or via the issue tracker on GitHub.

AUTHORS

       reptyr was written by Nelson Elhage <nelhage@nelhage.com>.

HOMEPAGE

       ⟨https://github.com/nelhage/reptyr⟩