{"record":{"id":"f6043a661fd53776","repo":"cloudflare/cloudflared","slug":"error-retrieving-output-from-command-s-w","errorCode":null,"errorMessage":"error retrieving output from command '%s': %w","messagePattern":"error retrieving output from command '(.+?)': %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"diagnostic/system_collector_linux.go","lineNumber":109,"sourceCode":"\t)\n\n\treturn info, gerror\n}\n\nfunc collectMemoryInformation(ctx context.Context) (*MemoryInformation, string, error) {\n\t// This function relies on the output of `cat /proc/meminfo` to retrieve\n\t// memoryMax and  memoryCurrent.\n\t// The expected output is in the format of `KEY VALUE UNIT`.\n\tconst (\n\t\tmemTotalPrefix     = \"MemTotal\"\n\t\tmemAvailablePrefix = \"MemAvailable\"\n\t)\n\n\tcommand := exec.CommandContext(ctx, \"cat\", \"/proc/meminfo\")\n\n\tstdout, err := command.Output()\n\tif err != nil {\n\t\treturn nil, \"\", fmt.Errorf(\"error retrieving output from command '%s': %w\", command.String(), err)\n\t}\n\n\toutput := string(stdout)\n\n\tmapper := func(field string) (uint64, error) {\n\t\tfield = strings.TrimRight(field, \" kB\")\n\n\t\treturn strconv.ParseUint(field, 10, 64)\n\t}\n\n\tmemoryInfo, err := ParseMemoryInformationFromKV(output, memTotalPrefix, memAvailablePrefix, mapper)\n\tif err != nil {\n\t\treturn nil, output, err\n\t}\n\n\t// returning raw output in case other collected information\n\t// resulted in errors\n\treturn memoryInfo, output, nil","sourceCodeStart":91,"sourceCodeEnd":127,"githubUrl":"https://github.com/cloudflare/cloudflared/blob/2253eeeb25a44a713a4b60b8ba1e1b3f377d1a0f/diagnostic/system_collector_linux.go#L91-L127","documentation":"collectMemoryInformation runs 'cat /proc/meminfo' and parses its output to build memory diagnostics. If command.Output() returns an error (non-zero exit, missing binary, I/O failure), this wrapped error including the command string is returned. On Linux this usually means /proc/meminfo is unreadable or the environment lacks cat.","triggerScenarios":"Collect called on Linux when /proc/meminfo cannot be read (procfs not mounted, e.g. some restricted containers/VMs), 'cat' is absent from PATH, or a seccomp/LSM policy denies the read.","commonSituations":"Hardened containers with masked /proc; minimal images without coreutils; sandboxed runtimes (gVisor etc.) with restricted procfs; compromised/oversized host where fd limits prevent spawning processes.","solutions":["Verify the file is readable: cat /proc/meminfo, as the same user running cloudflared.","Check that /proc is mounted and not fully masked in the container (--cap-add / volume mounts for /proc).","Ensure 'cat' exists in the image PATH (install coreutils/busybox).","Inspect the wrapped exec error: exit status vs exec.ErrNotFound vs permission error to target the fix."],"exampleFix":"// before\n# gVisor sandbox: cat /proc/meminfo -> no such file\n// after\n# run with procfs available or capture:\nvar ee *exec.ExitError\nif errors.As(err, &ee) { log stderr from ee.Stderr }\nvar nf *exec.Error\nif errors.As(err, &nf) { /* cat missing: install coreutils */ }","handlingStrategy":"validation","validationCode":"if _, err := os.ReadFile(\"/proc/meminfo\"); err != nil {\n\treturn fmt.Errorf(\"/proc/meminfo unreadable: %w\", err)\n}\nif _, err := exec.LookPath(\"cat\"); err != nil {\n\treturn fmt.Errorf(\"cat missing: %w\", err)\n}","typeGuard":null,"tryCatchPattern":"mem, _, err := systemCollect(ctx)\nvar nf *exec.Error\nif errors.As(err, &nf) {\n\t// cat not found: install coreutils\n} else if errors.As(err, &new(fs.PathError)) || strings.Contains(err.Error(), \"/proc/meminfo\") {\n\t// procfs unavailable/masked\n}","preventionTips":["Verify /proc/meminfo is readable in the target runtime (gVisor, masked /proc)","Include coreutils/busybox in minimal images","Test diagnostics after sandboxing/security policy changes","Prefer running diagnostics on the host namespace when in containers"],"tags":["diagnostics","linux","system-info","exec"],"backgroundTag":"command-failed","analyzedSha":"2253eeeb25a44a713a4b60b8ba1e1b3f377d1a0f","analyzedAt":"2026-09-06T04:14:33.757Z","contentChangedAt":"2026-09-06T04:14:33.757Z","schemaVersion":2},"datasetVersion":"2026-09-14T00:17:10.932Z"}