Where’s the Go standard package stored on your computer?

Go behind the scenes

You might wonder where the standard Go packages are installed and imported from ?

Let’s say you are importing “fmt” and “context” packages that are one of the most commonly imported packages in Go. But where do they come from ?

import (
"context"
"fmt"
)

You can see import statements like above sample code snippet.

As a matter of fact, those packages are living in “GOROOT”.

If you want to check where the GOROOT is, you can execute the command

$ go env GOROOT
/usr/local/Cellar/go/1.18.4/libexec

on my macOS machine, the GOROOT is “/usr/local/Cellar/go/1.18.4/libexec”

let’s take a look inside the directory then. You can see pretty standard structure of any Go modules like api, bin, lib, pkg, src, test etc…

➜  libexec ls -l /usr/local/Cellar/go/1.18.4/libexec
total 264
-rw-r--r--    1 yeongseokkim  admin    1339 Jul 13 00:22 CONTRIBUTING.md
-rw-r--r--    1 yeongseokkim  admin  111408 Jul 13 00:22 CONTRIBUTORS
-rw-r--r--    1 yeongseokkim  admin    1303 Jul 13 00:22 PATENTS
-rw-r--r--    1 yeongseokkim  admin     397 Jul 13 00:22 SECURITY.md
-rw-r--r--    1 yeongseokkim  admin       8 Jul 13 00:22 VERSION
drwxr-xr-x   24 yeongseokkim  admin     768 Jul 13 00:22 api
drwxr-xr-x    4 yeongseokkim  admin     128 Jul 13 00:22 bin
-rw-r--r--    1 yeongseokkim  admin      52 Jul 13 00:22 codereview.cfg
drwxr-xr-x    7 yeongseokkim  admin     224 Jul 13 00:22 doc
drwxr-xr-x    3 yeongseokkim  admin      96 Jul 13 00:22 lib
drwxr-xr-x   14 yeongseokkim  admin     448 Jul 13 00:22 misc
drwxr-xr-x    6 yeongseokkim  admin     192 Jul 13 00:22 pkg
drwxr-xr-x   69 yeongseokkim  admin    2208 Jul 13 00:22 src
drwxr-xr-x  354 yeongseokkim  admin   11328 Jul 13 00:22 test

Because the standard package is another module.

When the import statement starts without any path prefix but simply a package name like “context”, “fmt”. The package resolves its path to the standard packages.

and the packages are resolved from “src” folder of GOROOT.

if you list files and directories of src folder, you can see all standard packages including “context” and “fmt”.

➜  libexec ls -l src/               
total 184
-rw-r--r--    1 yeongseokkim  admin    553 Jul 13 00:22 Make.dist
-rw-r--r--    1 yeongseokkim  admin   2295 Jul 13 00:22 README.vendor
-rwxr-xr-x    1 yeongseokkim  admin    407 Jul 13 00:22 all.bash
-rw-r--r--    1 yeongseokkim  admin    754 Jul 13 00:22 all.bat
-rwxr-xr-x    1 yeongseokkim  admin    388 Jul 13 00:22 all.rc
drwxr-xr-x    4 yeongseokkim  admin    128 Jul 13 00:22 archive
-rwxr-xr-x    1 yeongseokkim  admin   3790 Jul 13 00:22 bootstrap.bash
drwxr-xr-x    8 yeongseokkim  admin    256 Jul 13 00:22 bufio
-rwxr-xr-x    1 yeongseokkim  admin   1872 Jul 13 00:22 buildall.bash
drwxr-xr-x    3 yeongseokkim  admin     96 Jul 13 00:22 builtin
drwxr-xr-x   12 yeongseokkim  admin    384 Jul 13 00:22 bytes
-rwxr-xr-x    1 yeongseokkim  admin    518 Jul 13 00:22 clean.bash
-rw-r--r--    1 yeongseokkim  admin    598 Jul 13 00:22 clean.bat
-rwxr-xr-x    1 yeongseokkim  admin    380 Jul 13 00:22 clean.rc
drwxr-xr-x   27 yeongseokkim  admin    864 Jul 13 00:22 cmd
-rw-r--r--    1 yeongseokkim  admin   1519 Jul 13 00:22 cmp.bash
drwxr-xr-x    8 yeongseokkim  admin    256 Jul 13 00:22 compress
drwxr-xr-x    5 yeongseokkim  admin    160 Jul 13 00:22 container
drwxr-xr-x    8 yeongseokkim  admin    256 Jul 13 00:22 context
drwxr-xr-x   23 yeongseokkim  admin    736 Jul 13 00:22 crypto
drwxr-xr-x    3 yeongseokkim  admin     96 Jul 13 00:22 database
drwxr-xr-x    9 yeongseokkim  admin    288 Jul 13 00:22 debug
drwxr-xr-x    5 yeongseokkim  admin    160 Jul 13 00:22 embed
drwxr-xr-x   14 yeongseokkim  admin    448 Jul 13 00:22 encoding
drwxr-xr-x    7 yeongseokkim  admin    224 Jul 13 00:22 errors
drwxr-xr-x    4 yeongseokkim  admin    128 Jul 13 00:22 expvar
drwxr-xr-x    8 yeongseokkim  admin    256 Jul 13 00:22 flag
drwxr-xr-x   15 yeongseokkim  admin    480 Jul 13 00:22 fmt
drwxr-xr-x   14 yeongseokkim  admin    448 Jul 13 00:22 go
-rw-r--r--    1 yeongseokkim  admin    288 Jul 13 00:22 go.mod
-rw-r--r--    1 yeongseokkim  admin    840 Jul 13 00:22 go.sum
drwxr-xr-x   12 yeongseokkim  admin    384 Jul 13 00:22 hash
drwxr-xr-x    9 yeongseokkim  admin    288 Jul 13 00:22 html
drwxr-xr-x   19 yeongseokkim  admin    608 Jul 13 00:22 image
drwxr-xr-x    3 yeongseokkim  admin     96 Jul 13 00:22 index
drwxr-xr-x   35 yeongseokkim  admin   1120 Jul 13 00:22 internal
drwxr-xr-x   12 yeongseokkim  admin    384 Jul 13 00:22 io
drwxr-xr-x    6 yeongseokkim  admin    192 Jul 13 00:22 log
-rwxr-xr-x    1 yeongseokkim  admin   7547 Jul 13 00:22 make.bash
-rw-r--r--    1 yeongseokkim  admin   4916 Jul 13 00:22 make.bat
-rwxr-xr-x    1 yeongseokkim  admin   3462 Jul 13 00:22 make.rc
drwxr-xr-x  125 yeongseokkim  admin   4000 Jul 13 00:22 math
drwxr-xr-x   20 yeongseokkim  admin    640 Jul 28 13:03 mime
drwxr-xr-x  203 yeongseokkim  admin   6496 Jul 13 00:22 net
drwxr-xr-x  120 yeongseokkim  admin   3840 Jul 13 00:22 os
drwxr-xr-x    8 yeongseokkim  admin    256 Jul 13 00:22 path
drwxr-xr-x    6 yeongseokkim  admin    192 Jul 13 00:22 plugin
-rwxr-xr-x    1 yeongseokkim  admin    884 Jul 13 00:22 race.bash
-rw-r--r--    1 yeongseokkim  admin   1091 Jul 13 00:22 race.bat
drwxr-xr-x   30 yeongseokkim  admin    960 Jul 13 00:22 reflect
drwxr-xr-x   14 yeongseokkim  admin    448 Jul 13 00:22 regexp
-rwxr-xr-x    1 yeongseokkim  admin   1851 Jul 13 00:22 run.bash
-rw-r--r--    1 yeongseokkim  admin   1034 Jul 13 00:22 run.bat
-rwxr-xr-x    1 yeongseokkim  admin    436 Jul 13 00:22 run.rc
drwxr-xr-x  624 yeongseokkim  admin  19968 Jul 13 00:22 runtime
drwxr-xr-x   19 yeongseokkim  admin    608 Jul 13 00:22 sort
drwxr-xr-x   34 yeongseokkim  admin   1088 Jul 13 00:22 strconv
drwxr-xr-x   18 yeongseokkim  admin    576 Jul 13 00:22 strings
drwxr-xr-x   27 yeongseokkim  admin    864 Jul 13 00:22 sync
drwxr-xr-x  316 yeongseokkim  admin  10112 Jul 13 00:22 syscall
drwxr-xr-x    3 yeongseokkim  admin     96 Jul 13 00:22 testdata
drwxr-xr-x   26 yeongseokkim  admin    832 Jul 13 00:22 testing
drwxr-xr-x    5 yeongseokkim  admin    160 Jul 13 00:22 text
drwxr-xr-x   37 yeongseokkim  admin   1184 Jul 13 00:22 time
drwxr-xr-x   14 yeongseokkim  admin    448 Jul 13 00:22 unicode
drwxr-xr-x    3 yeongseokkim  admin     96 Jul 13 00:22 unsafe
drwxr-xr-x    4 yeongseokkim  admin    128 Jul 13 00:22 vendor

They are coming along as a part of Go installation.

The Go source files for “context” package is there under “context” directory of src folder. and They look like this

➜  context ls -l
total 112
-rw-r--r--  1 yeongseokkim  admin   3845 Jul 13 00:22 benchmark_test.go
-rw-r--r--  1 yeongseokkim  admin  17825 Jul 13 00:22 context.go
-rw-r--r--  1 yeongseokkim  admin  19670 Jul 13 00:22 context_test.go
-rw-r--r--  1 yeongseokkim  admin   3054 Jul 13 00:22 example_test.go
-rw-r--r--  1 yeongseokkim  admin    538 Jul 13 00:22 net_test.go
-rw-r--r--  1 yeongseokkim  admin   1907 Jul 13 00:22 x_test.go

This knowledge about where the standard packages are installed isn’t really helping you out for programming skills, but it will make you get familiar with Go under the surface.

Thanks!