How does GDB's x (examine) command format work for reading memory, such as a jump table?

Question

Accepted Answer

x/NFU address — examine N items, in Format (x=hex, d=dec, i=instruction, s=string…), of Unit size (b/h/w/g = 1/2/4/8 bytes) — starting at address.
GDB's x is the Swiss-army knife for inspecting raw memory while reverse-engineering. The count, format, and unit are bundled into one slash-separated spec:
Format characters (F):

Char
Meaning

x
hexadecimal

t
binary

d
signed decimal

i
instruction

u
unsigned decimal

s
string

o
octal

Unit sizes (U):

Char
Size

b
byte (1)

h
halfword (2)

w
word (4)

g
giant word (8)

Examples:
(gdb) x/10xw 0x4000     # 10 hex words (4 bytes each)
(gdb) x/5i  main        # 5 instructions starting at main
(gdb) x/s   0x4005c8    # the string at that address
(gdb) x/7xg 0x4005c8    # 7 hex 8-byte values -> exactly a 7-entry jump table

Why x/7xg for a jump table: each x86_64 jump-table entry is an 8-byte (g) address, so reading 7 giant-words in hex dumps the table's targets — which you then match against the function's instruction addresses to decode which case goes where.
Go deeper:

GDB manual — the x (examine memory) command — the x command and its NFU format in the GDB manual.

Char	Meaning	Char	Meaning
x	hexadecimal	t	binary
d	signed decimal	i	instruction
u	unsigned decimal	s	string
o	octal