Well ... I don't usually read the GDB manual because its command line help is already quite good. To use GDB properly you should compile your C program with the -g switch. Then simply
gdb ./executable
Then you will be asked to enter the commands. I usually just type 'help' then you will see
Quote:
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
tui -- Text User Interface commands
user-defined -- User-defined commands
For example, to get a list of commands associated with running the program you type 'help running'.
To run the program, enter 'run'. Usually you may want to insert some breakpoints before starting the program. I forgot the command to use. You may type 'help breakpoints' for a list of commands that you will find useful.