Thread: Linux Program Extention?

Hey, if I wanted to compile something for Linux with g++ and I used -o, what should I name the file?

Just the name of the program?

Basically, I want to have it so I don't have to type "./a.out" to run my program, and instead, type "program"

File extensions under *nix don't mean anything
They are intended for humans only, and have no bearing on how the machine views the file

binary executables usually don't have an extension

Code:

g++ -o my_program my_program.cpp

Run the binary by typing

Code:

./my_program

For linux executables, I think the executable file needs to have it's executable "x" bits set in it's file permissions. You can find that out with a "ls -l", and set it (if it needs setting) using chmod. You also need to make sure the file's location is in your executable path.

Originally Posted by starry eyes

For linux executables, I think the executable file needs to have it's executable "x" bits set in it's file permissions. You can find that out with a "ls -l", and set it (if it needs setting) using chmod. You also need to make sure the file's location is in your executable path.

the compiler will do this automatically

Originally Posted by Ynot

File extensions under *nix don't mean anything
They are intended for humans only, and have no bearing on how the machine views the file

binary executables usually don't have an extension

Code:

g++ -o my_program my_program.cpp

Run the binary by typing

Code:

./my_program

Well, ls is a program, and so is Firefox, but I only have to type "ls" or "firefox" for it to run...how does that work?

the location of these programs is in your path variable

When asked to execute a program, the shell needs to know where the program is

you can do this in 3 ways

Give the absolute path to the binary
/bin/ls
/usr/bin/firefox
/home/user/program

Give a relative path (relative to the current directory)
./program - run "program" located in the current directory

Most "installed" programs, however, are located in special locations
When asked to execute a program with no location information, the shell will look through these special locations in order to find the program

These special locations are stored in the PATH variable

do

Code:

echo $PATH

If you want to be able to execute locally build programs without specifying their location, you need to add an additional directory to the path

Code:

mkdir ~/bin

compile all your programs into ~/bin, and you can just type the program name

Oh, okay.

Noob question, how do you add to the PATH variable?

If you make a bin directory in your home directory, you don't actually need to do anything

One thing Debian (and it's derivatives) do is look for a bin directory in your home directory, and add it to the path automatically

see ~/.profile

Code:

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

Btw,
when looking through the path variable for a program's location, the shell will take the first one it comes across

So, your path variable will look like

/home/user/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games

The search goes in order, left to right
so if you had a program called "foo" in /home/user/bin, and another (different) program called "foo" in /usr/local/bin
typing "foo" would execute the one in /home/user/bin

This means you can easily override programs with altered local versions, if you wish

make a program called "ls" in your ~/bin dir, and it'll always override the system installed ls command, unless you specify the absolute path of ls