Introspecting a machine’s uninstall information is one way to find what the machine currently installs and where it installs it, the install location. If you can uninstall something then you have something installed, surely, logically; see Figure 1. A Windows machine’s registry records how to remove installed programs.
Figure 1: Mind map
The example below uses R but the same principle applies to other languages provided that the language equips an interface to the Windows registry access functions.
Registry Hive
The local machine hive registers the local R installation with its version numbers and other interesting pieces of information. Reading the entire key extracts a named list.
is1 <- utils::readRegistry(
file.path("SOFTWARE", "Microsoft", "Windows", "CurrentVersion", "Uninstall",
paste("R for Windows 4.2.1", "is1", sep = "_"), fsep = "\\"),
hive = "HLM"
)| DisplayName | R for Windows 4.2.1 |
| DisplayVersion | 4.2.1 |
| EstimatedSize | 170133 |
| HelpLink | https://www.r-project.org |
| Inno Setup CodeFile: HelpStyle | HTML |
| Inno Setup CodeFile: MDISDI | MDI |
| Inno Setup: App Path | C:/Program Files/R/R-4.2.1 |
| Inno Setup: Deselected Components | |
| Inno Setup: Deselected Tasks | quicklaunchicon |
| Inno Setup: Icon Group | R |
| Inno Setup: Language | en |
| Inno Setup: Selected Components | main,x64,translations |
| Inno Setup: Selected Tasks | desktopicon,recordversion,associate |
| Inno Setup: Setup Type | user |
| Inno Setup: Setup Version | 6.2.0 |
| Inno Setup: User | royra |
| InstallDate | 20220628 |
| InstallLocation | C:/Program Files/R/R-4.2.1/ |
| MajorVersion | 4 |
| MinorVersion | 2 |
| NoModify | 1 |
| NoRepair | 1 |
| Publisher | R Core Team |
| QuietUninstallString | “C:/Program Files/R/R-4.2.1/unins000.exe” /SILENT |
| UninstallString | “C:/Program Files/R/R-4.2.1/unins000.exe” |
| URLInfoAbout | https://www.r-project.org |
| URLUpdateInfo | https://www.r-project.org |
| VersionMajor | 4 |
| VersionMinor | 2 |
The install location tells where the program lives on the local machine as a backslash-separated Windows folder path. (Back slashes replaced by forward in the above tabulation.)
is1$InstallLocation## [1] "C:\\Program Files\\R\\R-4.2.1\\"All Uninstallables
The R language can find all programs subject to removal. Search for all subkeys found under the local machine’s “software, Windows, current version, uninstall” registry key.
uninstall_key <- function(...)
file.path("SOFTWARE", "Microsoft", "Windows", "CurrentVersion", "Uninstall",
..., fsep = "\\")
uninstall <- utils::readRegistry(uninstall_key(), "HLM")
subkey <- names(uninstall)[uninstall == "<subkey>"]
hive <- lapply(uninstall_key(subkey), utils::readRegistry, "HLM")
names(hive) <- subkeyThe resulting hive is a list of lists, one list of properties for every hived uninstallable program.
hive$`R for Windows 4.2.1_is1`$InstallLocation## [1] "C:\\Program Files\\R\\R-4.2.1\\"Above gives the install location of R.