GDB commands control execution and inspection. Most commands have short abbreviations. Typing a blank line repeats the last command.

run (r)                start program
continue (c)           resume from breakpoint
next (n)               next line (skip calls)
step (s)               next line (step into calls)
finish                 run until return
until line             run until line reached
break (b) location     set breakpoint
watch variable         set watchpoint
print (p) expr         show expression value
backtrace (bt)         show call stack
frame N                select frame N
up / down              move between frames
list (l)               show source around current line
quit (q)               exit GDB
help command           show help
info breakpoints       list breakpoints
delete N               delete breakpoint N
disable N              disable (keep) breakpoint
enable N               enable breakpoint
display expr           auto-print expression
undisplay N            remove display

Abbreviations: most commands work with just the first letter. b for break, c for continue, n for next, s for step, p for print. Exceptions: u is ambiguous (could be until or up), so use the full name.

Blank line repeats the last command—useful for stepping (n, n, n by just pressing Enter). Stepping becomes very fast this way.

Command separators: separate multiple commands on one line with semicolons. break main; run; step sets a breakpoint at main, starts the program, and steps into main.

Sourcing commands: if you type the same sequence repeatedly, save commands to a file and run source filename in GDB. Each line is a command.

Shell escape: prefix a line with shell or ! to run a shell command. shell ls lists the current directory without leaving GDB.

Abbreviations are context-sensitive—if you type f 2, GDB interprets it as frame 2, not finish 2. Full names are safer in scripts.