Merged using 'Using gdb' notes

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diff --git a/md/writeup.md b/md/writeup.md
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+++ b/md/writeup.md
@@ -5,6 +5,7 @@
 [Using RTLSDR](writeup/rtlsdr_usage.md)  
 [Using mitmproxy](writeup/mitmproxy.md)  
 [Linux syscall table](notes/syscalls.md)  
+[Using GDB](writeup/using_gdb.md)
 
 # Archive
 [Create ELF file from scratch](http://archive.main.lv/writeup/create_elf_file_from_scratch.html)  
diff --git a/md/writeup/using_gdb.md b/md/writeup/using_gdb.md
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+# Using GDB
+
+GDB is gnu debugger that excists for years and it work on any linux/bsd
+ supported platform. And time to time there is situation when you definetly 
+whant debuger, just becouse of our favorite segfaults or just becose whant
+to solve at weekends evening some crackme. If you hace used some before
+some DOS debugers like Borland Turbo Debuger or just debug then comparing
+to gdb this are easy to use tools, and if you compare to OllyDbg then gdb is
+just nightmare =]. But yea there is no other choice then that 
+([ald](http://ald.sourceforge.net/)).
+
+Will add main points that are need to know to run/debug programm. With time
+more stuff will added
+
+## Run
+
+```bash
+gdb [PROGRAM]
+```
+
+```
+(gdb) run [CMD LINE PARAMS TO PROGRAM]
+```
+
+## Setting breakpoints
+
+Setting breakpoint on speific address
+
+```bash
+(gdb) break *0x800000
+```
+
+on specific function
+
+```bash
+(gdb) break _start
+```
+
+Here is more breakpoint types [Link1](http://ftp.gnu.org/old-gnu/Manuals/gdb/html_node/gdb_28.html) and [Link2](http://www.unknownroad.com/rtfm/gdbtut/gdbbreak.html) 
+
+## Print registers
+
+### Intel platform
+
+General purpose register values
+
+```bash
+(gdb) p $eax
+(gdb) p $ebx
+(gdb) p $ebp
+```
+
+print value in hex
+
+```bash
+(gdb) p/x $eax
+```
+
+
+
+## Print memory
+
+print one byte in specific adress
+```bash
+(gdb) x/u *0x808080
+```
+
+print array of 16 bytes in hex
+```bash
+gdb) x/16xu *0xffffd310
+```
+
+
+from register value
+
+```bash
+(gdb) x/4xb $ebp-0xc
+```
+
+## Print current position instruction
+
+```bash
+(gdb) x/i $pc
+```
+
+## Step
+
+```bash
+(gdb) step
+(gdb) next
+```
+
+### Links
+
+1. [http://althing.cs.dartmouth.edu/secref/resources/plt-got.txt](http://althing.cs.dartmouth.edu/secref/resources/plt-got.txt)
+2. [http://ftp.gnu.org/old-gnu/Manuals/gdb/html_node/gdb_28.html](http://ftp.gnu.org/old-gnu/Manuals/gdb/html_node/gdb_28.html)
+3. [http://www.unknownroad.com/rtfm/gdbtut/gdbbreak.html](http://www.unknownroad.com/rtfm/gdbtut/gdbbreak.html)
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