Building and Running Go-Programs

The go command

To compile and link a go program test.go, use:

go build test.go

If you want to compile, link and run the program, use:

go run test.go

where the executable binary is stored in the cache. If you want to compile, link and install the package pack1, use:

go install pack1

To remove any object and cache file, use:

go clean

Messages from the compiler

• If the build process (which is also called compile-time) doesn’t give any errors, no message appears.
• If building produces (an) error(s), we get the following output: ---- Build file exited with code 1, and the line number where the error occurs in the source-code is indicated, like this, if we insert var a at line 6: hello_world.go:6: syntax error: unexpected newline, expecting type
• In most IDEs, double-clicking the error line positions the editor on that code line where the error occurs.
• Go does not distinguish between warnings and errors. The philosophy is: when it is worth warning for misuse of something, it better be signaled as an error to be always on the safe side.
• If you try to execute a program which is not yet compiled, you get the following error: ---- Error run with code File not found, resource error.
• When executing a program, you are in the run-time environment. If the program executes correctly, after the execution the following is the output: ---- Program exited with code 0.

Compiling all go-files in a directory

Here is the Linux-version of a useful script for the purpose of quick testing for compilation errors in a lot of files:

#!/bin/bash
FILES=~/go_projects/src/*.go
for f in $FILES
do
echo "Processing $f file..."
# take action on each file. $f stores current filename
# cat $f
go build $f >> compout
done

You need to replace ~/go_projects/src/ with your folder name. This will compile all the go-files in the current directory and write the output to compout.

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That’s it about building and running a Go program via the command line. The next lesson discusses the help feature provided by Go.