file.access {base}R Documentation

Ascertain File Accessibility


Utility function to access information about files on the user's file systems.


file.access(names, mode = 0)


names character vector containing file names.
mode integer specifying access mode required.


The mode value can be the exclusive or of the following values

test for existence.
test for execute permission.
test for write permission.
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.


An integer vector with values 0 for success and -1 for failure.


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, try


fa <- file.access(dir("."))
table(fa) # count successes & failures

[Package base version 2.5.0 Index]