Quick Tip on Deleting Directories in R

When trying to delete a directory, one can encounter some unexpected problems. The function for carrying out this operation is unlink, which accepts the director name as its first argument; other arguments are recursive (a logical vector or length 1 indicating whether we want to delete subdirectories, and force, also logical, which tries to override file permissions in most cases. It returns 0 when successful and 1 when not.

But there is a gotcha to using the function. First let’s list the contents of the HOME directory

> list.files()
 [1] "3D Objects"
 [2] "AppData"
 [3] "Contacts"
 [4] "Desktop"
 [5] "Documents"
 [6] "Downloads"
 [7] "Favorites"
 [8] "IntelGraphicsProfiles"
 [9] "Links"
[10] "MicrosoftEdgeBackups"
[11] "Music"
[12] "New folder"
[13] "NTUSER.DAT"
[14] "ntuser.dat.LOG1"
[15] "ntuser.dat.LOG2"
[16] "NTUSER.DAT{a70b1724-6bc8-11e8-a408-d0bf9c58c5d2}.TM.blf"
[17] "NTUSER.DAT{a70b1724-6bc8-11e8-a408-d0bf9c58c5d2}.TMContainer00000000000000000001.regtrans-ms"
[18] "NTUSER.DAT{a70b1724-6bc8-11e8-a408-d0bf9c58c5d2}.TMContainer00000000000000000002.regtrans-ms"
[19] "ntuser.ini"
[20] "OneDrive"
[21] "Pictures"
[22] "R"
[23] "Saved Games"
[24] "Searches"
[25] "source"
[26] "Videos"

Let’s say we want to delete the ‘New folder’ directory

> (unlink('New folder/', recursive = TRUE, force = TRUE))
[1]

It fails!

Even when you study the help file, the source of this failure is not apparent.

Well, it turns out that the function does not recognize the trailing slash that indicates that we are dealing with a directory. This is always added when you use tab completion for the directory name.

So, when we type

# Remove trailing slash in directory name
> (unlink('New folder', recursive = TRUE, force = TRUE))
[0]

The function succeeds, as evidenced by listing the directory contents

> dir()
[1] "3D Objects"
[2] "AppData"
[3] "Contacts"
[4] "Desktop"
[5] "Documents"
[6] "Downloads"
[7] "Favorites"
[8] "IntelGraphicsProfiles"
[9] "Links"
[10] "MicrosoftEdgeBackups"
[11] "Music"
[12] "NTUSER.DAT"
[13] "ntuser.dat.LOG1"
[14] "ntuser.dat.LOG2"
[15] "NTUSER.DAT{a70b1724-6bc8-11e8-a408-d0bf9c58c5d2}.TM.blf"
[16] "NTUSER.DAT{a70b1724-6bc8-11e8-a408-d0bf9c58c5d2}.TMContainer00000000000000000001.regtrans-ms"
[17] "NTUSER.DAT{a70b1724-6bc8-11e8-a408-d0bf9c58c5d2}.TMContainer00000000000000000002.regtrans-ms"
[18] "ntuser.ini"
[19] "OneDrive"
[20] "Pictures"
[21] "R"
[22] "Saved Games"
[23] "Searches"
[24] "source"
[25] "Videos"

Watch out for this!

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