bootlogger is a command-line tool for Windows that logs system restart events, commonly known as a reboot. It records the date and time of each reboot, along with the computer name, and optionally the Windows version and build info. The log file name and location can be specified and the boot time can be formatted in any of more than a dozen date/time formats. bootlogger can also add itself to the Windows registry to run automatically at startup, ensuring that all reboots are logged. BTW, the name is "bootlogger", all lowercase.
Perhaps you've seen my Windows Update Viewer app or maybe Get My IP or one of the others. I needed to take a short break from maintaining those and felt like trying something new. I'd read good things about the Go language and decided to give it a go (pun intended). I was using a PowerShell script to log reboots, so I decided that rewriting it in Go would be a good first project. The result is what you see here. I found it easy to get started with Go. The Cobra and Viper packages made things a lot easier
bootlogger tries to get the computer name from the host name as reported by the kernel. If that fails, it tries to get the name from the COMPUTERNAME environment variable. If that also fails, it will use "unknown" for the computer name.
bootlogger uses the GetTickCount64 function to get the number of milliseconds that have elapsed since the system was started. That value is subtracted from the current date and time, giving the date and time of the last system start. That result is then formatted according to the timeformat configuration option discussed below.
bootlogger uses the registry to determine the Windows version and build information. Specifically, information found in HKLM\SOFTWARE\Microsoft\Windows NT\Current version\.
The version comes from the value of ProductName. Microsoft chose not to update this name from "Windows 10" when it released Windows 11. Therefore, if the Windows build number is equal to or greater than 22000, Windows 10 is changed to Windows 11 to accurately report the version of Windows.
The build number comes from combining the CurrentBuildNumber value with the UBR value giving the build number in the familiar xxxxx.yyyy format.
The computer name, reboot date and time, and the Windows version and build are written as a single record to the log file. As noted above, the logging of the version and build info is optional. That is controlled by the no-buildinfo option discussed below.
Running bootlogger without any additional commands or flags will write a record to the log file using the default configuration or the updated configuration found in environment variables, a configuration file, and/or command-line flags. Continue reading for examples.
Before discussing configuration, a few words about commands. Commands can be differentiated from flags by the fact that they don't begin with the dash, or two dashes, that flags use.
bootlogger has commands to perform some utility functions without writing a record to the log file. The first of these commands is help. Running bootlogger.exe help will show help for bootlogger.
bootlogger.exe version will show the version number.
bootlogger.exe printconfig will show the current configuration.
bootlogger.exe printlog will print the log file. Output can be piped through more for easier reading.
A tool that logs reboots wouldn't help much if you had to remember to run it after each reboot. bootlogger.exe autostart will allow you to enable or disable bootlogger from running at Windows startup,
or check its current status. When enabled, bootlogger will be added to the Windows startup registry key,
HKCU\Software\Microsoft\Windows\CurrentVersion\Run, allowing it to run automatically when Windows starts. If this doesn't work for you, it can be added to Task Scheduler or the to C:\Users\<user>\AppData\Roaming\Microsoft\Windows\Start Menu\Programs\Startup\.
Use bootlogger.exe [command] --help for more information about any of these commands.
bootlogger.exe printconfig
bootlogger configuration:
logfile = D:\Logs\bootlogger.test.log
namewidth = 12
no-buildinfo = true
no-text = false
quiet = false
timeformat = RFC822
bootlogger.exe autostart --enable
bootlogger was added to 'HKCU\Software\Microsoft\Windows\CurrentVersion\Run' and will run from: C:\PortableApps\bootlogger.exe when Windows starts.
bootlogger.exe version
bootlogger version: 0.1.0bootlogger can be configured through command-line flags, environment variables, or a configuration file.
Configurable options are:
| Option | Type | Default value | Description |
|---|---|---|---|
dryrun |
Boolean | false |
Write log line to console but not to the log file. Useful for testing. |
logfile |
String | bootlog.txt |
Log file filename with fully qualified (absolute) path. Use quotes if there are spaces in the path. |
namewidth |
Integer | 14 |
Minimum computer name width. Longer names are not truncated. Shorter names are padded with spaces. |
no-buildinfo |
Boolean | false |
Version and build info will not be included in the log entry. |
no-text |
Boolean | false |
The "was rebooted on" text will not be included in the log entry. |
quiet |
Boolean | false |
Quiet operation. Do not print non-error messages to the console. |
timeformat |
String | 12Hour |
Date/Time format. Use 12Hour for 12 hour, 24Hour for 24 hour or most of the Go pre-defined formats. DateOnly and TimeOnly are not included. See https://pkg.go.dev/time#pkg-constants for details. |
If used, the configuration file must be named config.yaml and must be in the same folder as bootlogger.exe. The configuration file must be in YAML format. YAML was chosen for its simple syntax and readability. If you aren't familiar with YAML, this Wikipedia article may help.
# Name of the log file
LogFile: "D:\Logs\bootlogger.test.log"
# Minimum width of the computer name field in the log
NameWidth: 12
# Time format. Either the custom 12-hour format or any of the Go pre-defined date/time formats.
TimeFormat: 24HourAll environment variables must be prefixed with BOOTLOG_ followed by the configuration option. That's a single underscore character between BOOTLOG and the option.
setx BOOTLOG_TIMEFORMAT 12Hour
setx BOOTLOG_No-Buildinfo trueTo configure bootlogger with command-line flags, prefix the configuration option with two consecutive dashes. So to configure the date/time format to use 24 hour time use bootlogger.exe -timeformat 24hour. Additional examples are found below.
Values for a flag can be separated by a space, separated by an equals sign, or follow the flag without a space.
Some command-line flags have a shorthand flag consisting of a single character. To use the shorthand flag, use only one dash before the character.
| flag | shorthand |
|---|---|
--help |
-h |
--logfile |
-l |
--namewidth |
-w |
--quiet |
-q |
--timeformat |
-t |
Note that --dryrun, --no-text and --no-buildinfo do not have shorthand flags.
Note that shorthand flags must be lower case.
bootlogger.exe --timeformat 12hour
Desktop-Computer was rebooted on 2025-06-19 7:43:19 AM [Windows 11 Pro build 26100.4061]
bootlogger.exe -t=24h
Desktop-Computer was rebooted on 2025-06-19 07:43:19 [Windows 11 Pro build 26100.4061]
bootlogger.exe --timeformat RFC822 --no-buildinfo
Desktop-Computer was rebooted on 19 Jun 25 07:43 CDT
bootlogger.exe --no-text
Desktop-Computer 2025-06-19 7:43:19 AM [Windows 11 Pro build 26100.4061]
bootlogger.exe --logfile d:\logs\bootlog.txt -q
#The entry will be made in the log file but nothing will be written to the console.
bootlogger.exe --dryrun
Dry run: the following line would be written to ./bootlogger.log
Desktop-Computer was rebooted on 2025-06-25 07:18:11 [Windows 11 Pro build 26100.4351]bootlogger is a "portable" app and as such doesn't require installation. Just copy the bootlogger.exe file to a folder where you have read and write permissions. Write permission is needed for the configuration file and for the log file itself.
The following packages were used in the development of bootlogger: