Linux programming

Programming in the Linux
Environment

ISO C and POSIX Standards
The Development tools
Using GCC
Creating and Using Libraries
Dynamic modules
Debugging with GDB

What are ISO C and POSIX
Standards and Why should we
care about them ?

The Development tools available in
the Linux Environment
– Programming Languages Available
✔ C

✔ C++

✔ Java

✔ Python

✔ C# (CLR comes from the Mono Project)

✔ Perl

✔ Tcl/tk

✔ Vala

✔ Lua

✔ Ada

✔ PHP

✔ Ruby

✔ Haskell, Pascal, Fortran, Lisp,

The Development tools available
in the Linux Environment
– Tools for C Programming
• GCC: GNU Compilers Collection
• GDB: GNU Debugger
• Emacs/Vi: The code editors

Using GCC
– Writing A “Hello World” Program
– Compiling and Running the program

gcc -o helloworld helloworld.c

./helloworld

Using GCC
– Some Essential features of GCC
• Including Additional Header Files

gcc -I/home/abhinav/code/include
include-test.c -o include-test

./include-test

Using GCC
– Some Essential features of GCC
• Linking Libraries
• Debugging symbols
• Creating libraries

– Libraries are a collection of functions
– libm, libpthread, libdbm, libc

Types of Libraries:
– Static Libraries: .a extension
– Dynamic Libraries: .so extension

– Making object files:

gcc -I./include -c new-helloworld.c print.c

– Linking Object files

• Gcc -o new-helloworld new-helloworld.o
print.o

-c : tells the compiler to only compile the
file, but not to link them
-o: to specify the name of the output file.

– Creating Static Library:

• gcc -o *.c

• ar cr libcalc.a *.o

– Linking against the static library:

gcc -I./include -o calc-test calc-test.c -L.
-lcalc

– Creating Shared Library:

• gcc -c -fPIC *.c

• gcc -shared -fPIC -o libcalc.so *.o

– Linking against the shared library:

(Same as linking against a static library)

gcc -I./include -o calc-test calc-test.c -L.
-lcalc

Debugging with GDB
– Generating debugging symbols:
• gcc -g -o

Starting the debugger:
• gdb <program name>

Some common commands:
• b line-number or function name: sets the break point
• next : step over
• step: step in
• p <variable name> : prints the value of the variable
• where: prints the stack trace
• up: moves you up in the stack

Dynamically Loading Modules

– Concept of Plugins/modules which are loaded by the program
at run tim
– No dynamic or statical linking of libraries

void *handle = dlopen(“libcalc.so”, RTLD_LAZY);
void (*test) () = dlsym(handle, “add”);
(*test) ();
dlclose (handle);

Some other productivity tools

Diff: What are the changes made in the file
Patch: merging the changes
Version Control tools: Git, Bazaar, mercurial, SVN, CVS

Thank You
--Abhinav Upadhyay
Twitter: iamabhi9
Irc.freenode.net: abhinav-

Linux programming

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