After building the executable, the file is not found

Help & Support
1

Hi there,

when I run my crystal-script via

crystal run src/main.cr

the script works fine

Now I try to build a executable:

crystal build src/main.cr

The file ‘main’ is created without any errors.

I change to the ‘src’ directory and want to start ‘main’:

cd src
main
Command 'main' not found, did you mean:
   command 'man' from deb man-db
   ...

Running crystal on Linux Ubuntu 22.04

Thanks for any help.

2

If I’m not mistaken, the compiler will put the compiled binary in the same directory as where you ran it. So it won’t be in src.

2 Likes
3

Yes, you are right. The file is in the same directory as I run the compiler. But I get the same Error.

One way to get it running is to move the file “main” in the subdirectory “/src”. Starting the programm from a directory-level lower works “src/main”.

My directory-structure is:

mf/src/main.cr
mf/lib/somelibs.cr
mf/output/someoutput.csv
mf/shard.yml

Here I run the compiler:

mf$ crystal build src/main.cr

As expected the binary is here:

mf/main

Trying to start the binary do not work

mf$ main

So I copy the binary to /src:

mf/src/main

Running the binary:

mf$ src/main

I do not understand, why the binary have to be in the “src”-folder and have to been startet from a different level. I’m afraid I’m making some fundamental mistake.

4

What is the actual error you get as to why it doesn’t work?

5

It sounds like the current working directory isn’t in $PATH (for good reasons). Try ./main instead

3 Likes
6

I do not understand, why the binary have to be in the “src”-folder and have to been startet from a different level. I’m afraid I’m making some fundamental mistake.

In order to run it you need to type:

./main

Short-hand example with an example structure from my point of view:

obraz
obraz1601×801 116 KB

7

crystal build src/main.crf -o src/main

this works under Ubuntu

8

The error is:

Command 'main' not found, did you mean:
   command 'man' from deb man-db
   ...

And since the command is not found, it will not work.

9

./main works fine. Thanks.
What does the ./?

10

It means it’s a file in your current directory.

For example if you wanted to copy a file that’s located at: /tmp/mysuperfile to your current directory you would use the ‘.’ as well:

cp /tmp/mysuperfile .

1 Like
11

So if I use main without a ./, the system doesn’t search in the directory I’m in right now?

12

yes. on *nix systems the current directory is not included in the search path.

if you are curious, you can show the searchpath with
echo $PATH

if you want to run something, it needs to be in a directory in the path, or you specify the location relative to your current directory, or the full path.

if the executable is in the current directory (assuming mf/)

./main
~/mf/main

if it is in the src folder and you are in the mf folder:

src/main
./src/main

Or globally whereever you are:

~/mf/src/main

The “~/” is substituted by the shell for your home directory and is a shorthand for /home//.

1 Like
13

Thanks! I still have a lot to learn about linux.
It’s often these little things that cause difficulties for beginners.

1 Like