Multiple commands in gdb separated by some sort of delimiter ';'?

Question

I am trying to execute two commands at once in gdb:

finish; next

I tried using the \';\' to separate the commands but gdb did not let me do

Answer 1

Certainly it is possible. Given, for example, C code

int a = 3;
double b = 4.4;
short c = 555;

, say we want to ask GDB what is the type of each of those variables.  The following sequence of GDB commands will allow us to enter 3 whatis requests all on a single line:

1. set prompt #gdb#
   • Any prompt whose first non-whitespace character is # will work: it just so happens that # starts a comment in GDB command scripts.
2. set logging overwrite on
   • By default, GDB appends to a log file; choosing to instead overwrite will let us easily deploy this trick again later, with different commands.
3. set logging redirect on
   • Meaning, save output of typed commands to log file only: do not also show it at the terminal. (Not absolutely required for our purposes, but keeps the clutter down.)
4. set logging on
   • This causes GDB to start actually logging; by default, the log file is called gdb.txt.
5. printf "\nwhatis a\nwhatis b\nwhatis c\n"
   • Our 3 whatis requests, entered on a single line as promised!  Separating the commands, before the first, and after the last is \n.
6. set logging off
   • Done writing to gdb.txt; that file now contains a valid GDB command script:

   #gdb#
   whatis a
   whatis b
   whatis c
   #gdb#

7. source gdb.txt
   • GDB now executes commands in the script which it just generated, producing the expected results:

type = int
type = double
type = short

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Notes

• Should you wish to deploy this trick again in the same GDB session, just perform steps 4-7.
• Generating a command script with shell would be less cumbersome, and may well be possible; the above method, however, is platform-agnostic.