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Using Lua's `os.rename` to rename a file from a hard drive to a new location on a USB flash drive

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−0

I'm using the os.rename function in a lua script. It works perfectly fine for renaming files on my hard drive, e.g.

os.rename("test.txt","/Users/username/Desktop/test2.txt")

will rename the file as desired.

However if the source file is on my hard drive and the target file is on a USB flash drive, the following operation

os.rename("test.txt","/Volumes/FLASHDRIVE/test2.txt")

will fail with the message

Cross-device link

which seems to indicate that the problem is that that source and target are on different file systems.

Is there any way to get os.rename to work in such a case or should I better resort to a workaround like

os.execute("mv  test.txt /Volumes/FLASHDRIVE/test2.txt")

?


I'm using

  • Lua 5.4.4
  • macOS 11.6.8
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Getting error message on failure (3 comments)

1 answer

+2
−0

Your diagnosis appears to be correct. Per https://www.lua.org/pil/22.html

Because Lua is written in ANSI C, it uses only the functions that the ANSI standard defines.

POSIX rename extends the definition of ANSI's rename with, in particular:

The rename() and renameat() functions shall fail if:
...
[EXDEV] The links named by new and old are on different file systems and the implementation does not support links between file systems.

So os.rename is not a solution and you need to either look for cross-platform libraries which implement a file move using other underlying functions or, as you suggest, use a platform-specific workaround.

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Thanks a lot for finding the relevant information! (1 comment)

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