R: Ascertain File Accessibility (original) (raw)
| file.access {base} | R Documentation |
|---|
Description
Utility function to access information about files on the user's file systems.
Usage
file.access(names, mode = 0)
Arguments
| names | character vector containing file names. Tilde-expansion will be done: see path.expand. |
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| mode | integer specifying access mode required: see ‘Details’. |
Details
The mode value can be the exclusive or (xor), i.e., a partial sum of the following values, and hence must be in 0:7,
0
test for existence.
1
test for execute permission.
2
test for write permission.
4
test for read permission.
Permission will be computed for real user ID and real group ID (rather than the effective IDs).
Please note that it is not a good idea to use this function to test before trying to open a file. On a multi-tasking system, it is possible that the accessibility of a file will change between the time you call file.access() and the time you try to open the file. It is better to wrap file open attempts in [try](../../base/help/try.html).
Value
An integer vector with values 0 for success and -1 for failure.
Note
This was written as a replacement for the S-PLUS functionaccess, a wrapper for the C function of the same name, which explains the return value encoding. Note that the return value isfalse for success.
See Also
[file.info](../../base/help/file.info.html) for more details on permissions,[Sys.chmod](../../base/help/Sys.chmod.html) to change permissions, and[try](../../base/help/try.html) for a ‘test it and see’ approach.
[file_test](../../utils/html/filetest.html) for shell-style file tests.
Examples
fa <- file.access(dir("."))
table(fa) # count successes & failures
[Package _base_ version 4.6.0 Index]