-m,-mapped

Warning: this option depends on operating system facilities

 

that are not supported on all systems.

 

If memory-mapped files are available on your system

 

through the mmap system call, you can use this option

 

to have GDB write the symbols from your program

 

into a reusable file in the current directory. If the

 

program you are debugging is called '/tmp/fred', the

 

mapped symbol file is '/tmp/fred.syms'. Future GDB

 

debugging sessions notice the presence of this file, and

 

can quickly map in symbol information from it, rather

 

than reading the symbol table from the executable

 

program.

 

The '.syms' file is specific to the host machine where

 

GDB is run. It holds an exact image of the internal GDB

 

symbol table. It cannot be shared across multiple host

 

platforms.

-r,-readnow

Read each symbol file's entire symbol table

 

immediately, rather than the default, which is to read

 

it incrementally as it is needed. This makes startup

 

slower, but makes future operations faster.

You typically combine the -mappedand -readnowoptions in order to build a '.syms' file that contains complete symbol information. (See “Commands to specify files” (page 125), for information on '.syms' files.) A simple GDB invocation to do nothing but build a '.syms' file for future use is:

gdb -batch -nx -mapped -readnow programname

2.1.2 Choosing modes

You can run GDB in various alternative modes―for example, in batch mode or quiet mode.

-nx,-n

Do not execute commands found in any initialization

 

files (normally called '.gdbinit', or 'gdb.ini' on PCs).

 

Normally, GDB executes the commands in these files

 

after all the command options and arguments have been

 

processed. See “Command files” (page 289).

-quiet,-silent,-q

“Quiet”. Do not print the introductory and copyright

 

messages. These messages are also suppressed in batch

 

mode.

-batch

Run in batch mode. Exit with status 0 after processing

 

all the command files specified with '-x' (and all

 

commands from initialization files, if not inhibited with

2.1 Invoking GDB 27