Question

I have an array of characters with about 100k entries. It seems like when in the function I
print *buffer it is getting cut off prematurely. is there anything I can do to lengthen the amount of characters gdb will print to console? If not, can I print this variable to file? I tried to use the dump commands, but couldnt seem to come up with the right thing.

Answer 1

(gdb) help x
Examine memory: x/FMT ADDRESS.
ADDRESS is an expression for the memory address to examine.
FMT is a repeat count followed by a format letter and a size letter.
Format letters are o(octal), x(hex), d(decimal), u(unsigned decimal),
  t(binary), f(float), a(address), i(instruction), c(char) and s(string).
Size letters are b(byte), h(halfword), w(word), g(giant, 8 bytes).
The specified number of objects of the specified size are printed
according to the format.

Defaults for format and size letters are those previously used.
Default count is 1.  Default address is following last thing printed
with this command or "print".
(gdb) x/8b array
0xbffd7670:     0       0       0       0       0       0       0       0
(gdb) x/16b array
0xbffd7670:     0       0       0       0       0       0       0       0
0xbffd7678:     0       0       0       0       0       0       0       0
(gdb) x/128b array
0xbffd7670:     0       0       0       0       0       0       0       0
0xbffd7678:     0       0       0       0       0       0       0       0
0xbffd7680:     0       0       0       0       0       0       0       0
0xbffd7688:     0       0       0       0       0       0       0       0
0xbffd7690:     0       0       0       0       0       0       0       0
0xbffd7698:     0       0       0       0       0       0       0       0
0xbffd76a0:     0       0       0       0       0       0       0       0
0xbffd76a8:     0       0       0       0       0       0       0       0
0xbffd76b0:     0       0       0       0       0       0       0       0
0xbffd76b8:     0       0       0       0       0       0       0       0
0xbffd76c0:     0       0       0       0       0       0       0       0
0xbffd76c8:     0       0       0       0       0       0       0       0
0xbffd76d0:     0       0       0       0       0       0       0       0
0xbffd76d8:     0       0       0       0       0       0       0       0
0xbffd76e0:     0       0       0       0       0       0       0       0
0xbffd76e8:     0       0       0       0       0       0       0       0
(gdb)

If you want the ASCII character symbols printed as well, use x/<size>c.

(gdb) set logging file ~/gdb_dump.txt
(gdb) set logging on
Copying output to /home/mminich/gdb_dump.txt.
(gdb) x/26c array
0xbfff4b20:     97 'a'  98 'b'  99 'c'  100 'd' 101 'e' 102 'f' 103 'g' 104 'h'
0xbfff4b28:     105 'i' 106 'j' 107 'k' 108 'l' 109 'm' 110 'n' 111 'o' 112 'p'
0xbfff4b30:     113 'q' 114 'r' 115 's' 116 't' 117 'u' 118 'v' 119 'w' 120 'x'
0xbfff4b38:     121 'y' 122 'z'
(gdb) set logging off
Done logging to /home/mminich/gdb_dump.txt.
(gdb)

BTW, I agree wholeheartedly with William Pursell’s comment under your question: “I find it much easier to define functions in the code that perform the data dump, and just call them from gdb. (Wrap the definitions in #ifdef DEBUG)”