file.access               package: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:

     Tilde-expansion is done on 'names': see 'path.expand'.

     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.  It is better to wrap file open attempts in 'try'.

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

