fileAccess
Checks the permission of a file or a directory
Checks the permission of a file or a directory.
- Keywords
- programming, IO
Usage
# S3 method for default
fileAccess(pathname, mode=0, safe=TRUE, ...)Arguments
- pathname
A
characterstring of the file or the directory to be checked.- mode
An
integer(0,1,2,4), cf.file.access().- safe
If
TRUE, the permissions are tested more carefully, otherwisefile.access() is used.- ...
Not used.
Details
In R there is file.access() for checking whether the
permission of a file.
Unfortunately, that function cannot be 100% trusted depending on
platform used and file system queried, cf. [1].
Value
Returns an integer; 0 if the permission exists, -1 if not.
Symbolic links
This function follows symbolic links (also on Windows) and returns a value based on the link target (rather than the link itself).
References
[1] R-devel thread file.access() on network (mounted) drive on Windows Vista? on Nov 26, 2008. https://stat.ethz.ch/pipermail/r-devel/2008-December/051461.html [2] Filesystem permissions, Wikipedia, 2010. http://en.wikipedia.org/wiki/Filesystem_permissions
See Also
Examples
# NOT RUN {
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Current directory
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
path <- "."
# Test for existence
print(fileAccess(path, mode=0))
# Test for execute permission
print(fileAccess(path, mode=1))
# Test for write permission
print(fileAccess(path, mode=2))
# Test for read permission
print(fileAccess(path, mode=4))
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# A temporary file
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
pathname <- tempfile()
cat(file=pathname, "Hello world!")
# Test for existence
print(fileAccess(pathname, mode=0))
# Test for execute permission
print(fileAccess(pathname, mode=1))
# Test for write permission
print(fileAccess(pathname, mode=2))
# Test for read permission
print(fileAccess(pathname, mode=4))
file.remove(pathname)
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# The 'base' package directory
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
path <- system.file(package="base")
# Test for existence
print(fileAccess(path, mode=0))
# Test for execute permission
print(fileAccess(path, mode=1))
# Test for write permission
print(fileAccess(path, mode=2))
# Test for read permission
print(fileAccess(path, mode=4))
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# The 'base' package DESCRIPTION file
# - - - - - - - - - - - - - - - - - - - - - - - - - - - -
pathname <- system.file("DESCRIPTION", package="base")
# Test for existence
print(fileAccess(pathname, mode=0))
# Test for execute permission
print(fileAccess(pathname, mode=1))
# Test for write permission
print(fileAccess(pathname, mode=2))
# Test for read permission
print(fileAccess(pathname, mode=4))
# }