What causes "could not create CPU profile: %w" in junegunn/fzf?

Create the parent directory first: mkdir -p /tmp/prof

could not create CPU profile: %w

Error message

could not create CPU profile: %w

What it means

In a pprof-enabled build (go build -tags=pprof), fzf failed to create the output file for the CPU profile given via --profile-cpu. The wrapped OS error (permission denied, no such directory, etc.) tells you why os.Create failed.

Source

Thrown at src/options_pprof.go:19

//go:build pprof
// +build pprof

package fzf

import (
	"fmt"
	"os"
	"runtime"
	"runtime/pprof"

	"github.com/junegunn/fzf/src/util"
)

func (o *Options) initProfiling() error {
	if o.CPUProfile != "" {
		f, err := os.Create(o.CPUProfile)
		if err != nil {
			return fmt.Errorf("could not create CPU profile: %w", err)
		}

		if err := pprof.StartCPUProfile(f); err != nil {
			return fmt.Errorf("could not start CPU profile: %w", err)
		}

		util.AtExit(func() {
			pprof.StopCPUProfile()
			if err := f.Close(); err != nil {
				fmt.Fprintln(os.Stderr, "Error: closing cpu profile:", err)
			}
		})
	}

	stopProfile := func(name string, f *os.File) {
		if err := pprof.Lookup(name).WriteTo(f, 0); err != nil {
			fmt.Fprintf(os.Stderr, "Error: could not write %s profile: %v\n", name, err)
		}

View on GitHub (pinned to bd4efa277b)

Solutions

Create the parent directory first: mkdir -p /tmp/prof
Point --profile-cpu at an existing writable directory
Check the wrapped error text for the exact OS reason

Example fix

# before
fzf --profile-cpu /nonexistent/cpu.prof
# after
mkdir -p /tmp/prof && fzf --profile-cpu /tmp/prof/cpu.prof

Defensive patterns

Strategy: validation

Validate before calling

prof_dir=/tmp/fzf-prof; mkdir -p "$prof_dir" && [ -w "$prof_dir" ] || exit 1
fzf --profile-cpu "$prof_dir/cpu.prof"

Prevention

mkdir -p the profile directory in the same command
Use absolute paths so cwd changes cannot break profiling

When it happens

Trigger: Passing --profile-cpu /path/cpu.prof where the directory does not exist, is not writable, or the path is a directory itself; initProfiling runs during option initialization and aborts startup.

Common situations: Profiling into a temp dir that was cleaned up; profiling paths with typos; running as a user without write access to the target directory.

Related errors

AI-assisted analysis of junegunn/fzf@bd4efa277b (2026-08-15). Data as JSON: /api/errors/4846d4e5108d489a. Report an issue: GitHub.