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Full Discussion: gcc linker address
Top Forums Programming gcc linker address Post 302489701 by Corona688 on Friday 21st of January 2011 10:08:13 AM
Old 01-21-2011
Quote:
Originally Posted by Praveen_218
I, however, really couldn't figure out this 0x08048000 location in the realelf output of your example???
I think that's because crt1.o is a library. That stuff gets decided when the final executable is linked and not before.
Quote:
000000000040069a 82 FUNC GLOBAL DEFAULT 12 main
That's because:
Quote:
Originally Posted by Corona688
main's location ... doesn't need to be at anywhere in particular.

There is a tiny bit of code that's at a fixed location. When the executable loads, it doesn't call any functions -- it just jumps immediately to 0x08048000(for linux x86 anyway, won't speak for other architectures) and begins executing whatever's there.
The bit that ends up at the start location is called _start.

The start location might have been even less fixed than I thought, too. 0x08048000 is just where linux x86 begins loading code for x86, not where _start has to be.

Last edited by Corona688; 01-21-2011 at 11:15 AM..
 

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SHELL-QUOTE(1)						User Contributed Perl Documentation					    SHELL-QUOTE(1)

NAME
shell-quote - quote arguments for safe use, unmodified in a shell command SYNOPSIS
shell-quote [switch]... arg... DESCRIPTION
shell-quote lets you pass arbitrary strings through the shell so that they won't be changed by the shell. This lets you process commands or files with embedded white space or shell globbing characters safely. Here are a few examples. EXAMPLES
ssh preserving args When running a remote command with ssh, ssh doesn't preserve the separate arguments it receives. It just joins them with spaces and passes them to "$SHELL -c". This doesn't work as intended: ssh host touch 'hi there' # fails It creates 2 files, hi and there. Instead, do this: cmd=`shell-quote touch 'hi there'` ssh host "$cmd" This gives you just 1 file, hi there. process find output It's not ordinarily possible to process an arbitrary list of files output by find with a shell script. Anything you put in $IFS to split up the output could legitimately be in a file's name. Here's how you can do it using shell-quote: eval set -- `find -type f -print0 | xargs -0 shell-quote --` debug shell scripts shell-quote is better than echo for debugging shell scripts. debug() { [ -z "$debug" ] || shell-quote "debug:" "$@" } With echo you can't tell the difference between "debug 'foo bar'" and "debug foo bar", but with shell-quote you can. save a command for later shell-quote can be used to build up a shell command to run later. Say you want the user to be able to give you switches for a command you're going to run. If you don't want the switches to be re-evaluated by the shell (which is usually a good idea, else there are things the user can't pass through), you can do something like this: user_switches= while [ $# != 0 ] do case x$1 in x--pass-through) [ $# -gt 1 ] || die "need an argument for $1" user_switches="$user_switches "`shell-quote -- "$2"` shift;; # process other switches esac shift done # later eval "shell-quote some-command $user_switches my args" OPTIONS
--debug Turn debugging on. --help Show the usage message and die. --version Show the version number and exit. AVAILABILITY
The code is licensed under the GNU GPL. Check http://www.argon.org/~roderick/ or CPAN for updated versions. AUTHOR
Roderick Schertler <roderick@argon.org> perl v5.16.3 2010-06-11 SHELL-QUOTE(1)
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