List of classes of commands:

aliases -- Aliases of other commands
breakpoints -- Making program stop at certain points
data -- Examining data
files -- Specifying and examining files
internals -- Maintenance commands
obscure -- Obscure features
running -- Running the program
stack -- Examining the stack
status -- Status inquiries
support -- Support facilities
tracepoints -- Tracing of program execution without stopping the program
user-defined -- User-defined commands

Type "help" followed by a class name for a list of commands in that class.
Type "help all" for the list of all commands.
Type "help" followed by command name for full documentation.
Type "apropos word" to search for commands related to "word".
Command name abbreviations are allowed if unambiguous.
Undefined command: "running".  Try "help".
The program being debugged has been started already.
Start it from the beginning? (y or n) Program not restarted.
Continuing.

Program received signal SIGUSR1, User defined signal 1.
0x00007fe5b539f6e3 in select () from /lib/x86_64-linux-gnu/libc.so.6
Detaching from program: /usr/bin/Xorg, process 949
Continuing.

Program received signal SIGSEGV, Segmentation fault.
0x00007fb8c2c0893f in glamor_poly_segment_solid_gl (drawable=0x7fb8c7544010, 
    gc=0x7fb8c98de36a, nseg=20, 
    segs=0x7fb8c98de2c4)
    at ../../glamor/glamor_segs.c:80
warning: Source file is more recent than executable.
80	            v[j++] = segs[i];
Detaching from program: /usr/bin/Xorg, process 1238