# How to Change Open Files Limit on OS X and macOS

_This text is the section about OS X Yosemite (which also works for macOS Sierra) from https://docs.basho.com/riak/kv/2.1.4/using/performance/open-files-limit/#mac-os-x_

_The last time i visited this link it was dead (403), so I cloned it here from the latest snapshot in Archive.org's Wayback Machine
https://web.archive.org/web/20170523131633/https://docs.basho.com/riak/kv/2.1.4/using/performance/open-files-limit/_

## Mac OS X

### To check the current limits on your Mac OS X system, run:

```shell
launchctl limit maxfiles
```

The last two columns are the soft and hard limits, respectively.

### Adjusting Open File Limits in Yosemite

To adjust open files limits on a system-wide basis in Mac OS X Yosemite, you must create two configuration files. The first is a property list (aka plist) file in `/Library/LaunchDaemons/limit.maxfiles.plist` that contains the following XML configuration:

```xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
  <plist version="1.0">
    <dict>
      <key>Label</key>
        <string>limit.maxfiles</string>
      <key>ProgramArguments</key>
        <array>
          <string>launchctl</string>
          <string>limit</string>
          <string>maxfiles</string>
          <string>200000</string>
          <string>200000</string>
        </array>
      <key>RunAtLoad</key>
        <true/>
      <key>ServiceIPC</key>
        <false/>
    </dict>
  </plist>
```
  
This will set the open files limit to 200000. The second plist configuration file should be stored in `/Library/LaunchDaemons/limit.maxproc.plist` with the following contents:

```xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple/DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
  <plist version="1.0">
    <dict>
      <key>Label</key>
        <string>limit.maxproc</string>
      <key>ProgramArguments</key>
        <array>
          <string>launchctl</string>
          <string>limit</string>
          <string>maxproc</string>
          <string>2048</string>
          <string>2048</string>
        </array>
      <key>RunAtLoad</key>
        <true />
      <key>ServiceIPC</key>
        <false />
    </dict>
  </plist>
```

Both plist files must be owned by root:wheel and have permissions -rw-r--r--. This permissions should be in place by default, but you can ensure that they are in place by running sudo chmod 644 <filename>. While the steps explained above will cause system-wide open file limits to be correctly set upon restart, you can apply them manually by running launchctl limit.

In addition to setting these limits at the system level, we recommend setting the at the session level as well by appending the following lines to your bashrc, bashprofile, or analogous file:

```shell
ulimit -n 200000
ulimit -u 2048
```

Like the plist files, your bashrc or similar file should have -rw-r--r-- permissions. At this point, you can restart your computer and enter `ulimit -n` into your terminal. If your system is configured correctly, you should see that maxfiles has been set to 200000.