---
name: "iofileb.d"
section: "1m"
platform: "macos"
package: "dtrace"
version: "413"
release: "macOS 26.5"
platforms: ["macos"]
url: "https://new.carta.tech/iofileb.d"
---

# iofileb.d(1m)

I/O bytes by file and process. Uses DTrace.

## NAME

iofileb.d - I/O bytes by file and process. Uses DTrace.

## SYNOPSIS

**iofileb.d**

## DESCRIPTION

This prints a summary of requested disk activity by pathname, providing totals of the I/O events in bytes. It is a companion to the iofile.d script - which prints in terms of I/O wait time, not bytes. I/O wait time is a better metric for understanding performance issues. Both disk and NFS I/O are measured.

Since this uses DTrace, only users with root privileges can run this command.

## EXAMPLES

- Sample until Ctrl-C is hit then print report,

  \#  **iofileb.d**

## FIELDS

- PID

  process ID

- CMD

  process name

- KB

  kilobytes of disk I/O

- FILE

  file pathname

## DOCUMENTATION

See the DTraceToolkit for further documentation under the  Docs directory. The DTraceToolkit docs may include full worked examples with verbose descriptions explaining the output.

## EXIT

iofileb.d will sample until Ctrl-C is hit.

## SEE ALSO

iofile.d(1M), iosnoop(1M), dtrace(1M)