| file.access {base} | R Documentation |
Ascertain File Accessibility
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. |
mode |
integer specifying access mode required. |
Details
The mode value can be the exclusive or of the following values
- 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 good 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, and in
recent Windows versions the underlying function in msvcrt.dll
sometimes returns inaccurate values. It is better to wrap
file open attempts in try instead.
Value
An integer vector with values 0 for success and -1 for failure.
Note
This is intended as a replacement for the S-PLUS function
access, a wrapper for the C function of the same name, which
explains the return value encoding. Note that
the return value is false for success.
See Also
file.info, try
Examples
fa <- file.access(dir("."))
table(fa) # count successes & failures