What causes "%s exists but is not executable" in golang/go?

Run `chmod 0755 file` in the script before the exists -exec check.

%s exists but is not executable

Error message

%s exists but is not executable

What it means

Thrown by the exists command (with -exec flag) in the Go test script framework when a file exists but has no execute permission bits set (mode & 0o111 == 0). This check is skipped on Windows (runtime.GOOS != "windows"). The command asserts that files should be executable.

Source

Thrown at src/cmd/internal/script/cmds.go:617

				default:
					break loop
				}
			}
			if len(args) == 0 {
				return nil, ErrUsage
			}

			for _, file := range args {
				file = s.Path(file)
				info, err := os.Stat(file)
				if err != nil {
					return nil, err
				}
				if readonly && info.Mode()&0222 != 0 {
					return nil, fmt.Errorf("%s exists but is writable", file)
				}
				if exec && runtime.GOOS != "windows" && info.Mode()&0111 == 0 {
					return nil, fmt.Errorf("%s exists but is not executable", file)
				}
			}

			return nil, nil
		})
}

// Grep checks that file content matches a regexp.
// Like stdout/stderr and unlike Unix grep, it accepts Go regexp syntax.
//
// Grep does not modify the State's stdout or stderr buffers.
// (Its output goes to the script log, not stdout.)
func Grep() Cmd {
	return Command(
		CmdUsage{
			Summary: "find lines in a file that match a pattern",
			Args:    matchUsage + " file",
			Detail: []string{

View on GitHub (pinned to b6b368adc5)

Solutions

Run `chmod 0755 file` in the script before the exists -exec check.
Use `cp -perm=0755` or ensure the build step produces an executable-mode file.
On Windows this check is skipped; ensure you're testing on the intended platform.

Example fix

// Before:
// exists -exec mybin
//
// After (add chmod first):
// chmod 0755 mybin
// exists -exec mybin

Defensive patterns

Strategy: validation

Validate before calling

// Ensure file is executable before asserting exists -exec:
// In the test script:
// chmod 0755 mybin
// exists -exec mybin

// Programmatic check:
func ensureExecutable(path string) error {
    info, err := os.Stat(path)
    if err != nil { return err }
    if runtime.GOOS != "windows" && info.Mode() & 0111 == 0 {
        return os.Chmod(path, info.Mode()|0100)
    }
    return nil
}

Prevention

Always chmod binaries to include execute bits before exists -exec assertions.
Use 0755 for executables in test scripts.
Ensure cp or build steps preserve or set executable permissions.

When it happens

Trigger: exists -exec <file> is called on a non-Windows platform and os.Stat returns a mode where none of the three execute bits (0o100, 0o010, 0o001) are set. The check is `info.Mode()&0111 == 0`.

Common situations: Test script builds or copies a binary but doesn't set the executable bit, then asserts it should be executable. Common after `cp` without preserving mode, or when creating a file from content without chmod. Also happens with cross-compiled binaries that haven't been chmod'd.

Related errors

AI-assisted analysis of golang/go@b6b368adc5 (2026-08-12). Data as JSON: /api/errors/355cd5b35e15d54e. Report an issue: GitHub.