How to 'read' programs

[reasonit]

So I know a bit of C# , php and a bit of C.
what I really want to do is modify some linux programs to suit my needs.

basically how does one 'read' or understand a program ? Lets take jwm for example, lets say I want to add the ability to close applications by middle clicking on them in the taskbar: how do I go about understanding it ? Is there a method to it? I downloaded the source, opened a few C files . didn't understand I thing.

Should I first wet my feet with simpler C programs ? If so can someone suggest me some? I am interested in 'real' C linux programs.

Thanks

[Lobster]

http://puppylinux.org/wikka/compiling

[L18L]

...
Should I first wet my feet with simpler C programs ? If so can someone suggest me some? I am interested in 'real' C linux programs.
...

hello

[dejan555]

You download program's source code obviously and modify what you want then compile it.

[muggins]

And of course backup, backup & backup. Definitely start with small, simpler programs.

[Bruce B]

Should I first wet my feet with simpler C programs ?
If so can someone suggest me some? I am interested in 'real' C linux
programs.

Thanks

This is real C. It is as trivial as it comes for a do something utility. It is
used as a pipe. Takes character input and outputs in hex.

Take a bite on it. Then Muggins or I can explain.

Code: Select all

#include <stdio.h>

int main() {

register int ch;

    while((ch=getchar()) != EOF) {

        if ( ch == 10 ) {
            printf ("0a ");
            continue;
        }

        printf ("%0x ", ch);

    }

    return(0);

}

~

[L18L]

Take a bite on it.

May I join the playground ?

half bit of C, some php, bash and BaCon....

I am coming here from testing wary51157 running as fido, devx installed.

Code: Select all

mkdir ~/programming/C

copied code into char2hex.c
compiled (fido can !)

Code: Select all

# gcc char2hex.c

and used it:

Code: Select all

# echo "123" |  ./a.out
31 32 33 0a 

Code: Select all

# pwd
/root/programming/C
# whoami
fido

# echo "Thank you" | ./a.out
54 68 61 6e 6b 20 79 6f 75 0a #

[Bruce B]

L18L,

This is the bash script to reassemble the hex. You should be able to
take the output of char2hex, even on a complex file like a binary file
and reassemble with perfect md5sum match. Moreover, if not
perfect something is wrong.

The script doesn't work like it looks like it works. It is strictly a pipe.
Use it the same as the char2hex.

It only works on the hex input format like char2hex outputs.

Code: Select all

#!/bin/bash
for i in `cat $1` ; do
	printf "\x$i"
done

cat filename.txt | char2hex | hex2char

So, you know by the command that filename.txt was converted to
the hex output, piped to hex2char and prints the text again.

For a binary file

cat filename.bin | char2hex

But not this

cat filename.bin | char2hex | hex2char

The reason why is there are often characters in the .bin file which
shouldn't be printed to the screen and locks up your bash terminal

In simple words. Don't output things to screen which crash the
monitor.

Bruce

~

[L18L]

...
This is the bash script to reassemble the hex. You should be able to
take the output of char2hex, even on a complex file like a binary file
and reassemble with perfect md5sum match. Moreover, if not
perfect something is wrong.
...

Thank you, Bruce
For me it was working.

But first let me point to the story that might give an explanation to OP and others.

And then admit: If had completely read this before my example would have been better.
Not:

Code: Select all

# gcc char2hex.c

But:

Code: Select all

gcc char2hex.c -o char2hex

Anyway I had to use it with a.out instead of char2hex
No: with .a.aut

OT ?
- the dots are important
- fido can

Thanks again

[abushcrafter]

Great idea! Close window on middle click. I love it . I hope it gets added to JWM.

[jpeps]

Great idea! Close window on middle click. I love it . I hope it gets added to JWM.

Middle button typically pastes the clipboard, which might be a conflict.

[Bruce B]

Keyboard shortcuts for closing most apps

Ctrl+q

Alt+F4

~

[abushcrafter]

Great idea! Close window on middle click. I love it . I hope it gets added to JWM.

Middle button typically pastes the clipboard, which might be a conflict.

Sorry, I meant on the task bar buttons.

[Bruce B]

nice share bruceb. Did know about the ctrl Q shortcut

Keyboard shortcuts are often listed on the drop down menus. See the picture for Firefox's 'File' menu below.

~