Extract File Information

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Description

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

Usage

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Arguments

...

character vectors containing file paths. Tilde-expansion is done: see path.expand.

extra_cols

Logical: return all cols rather than just the first six.

Details

What constitutes a ‘file’ is OS-dependent but includes directories. (However, directory names must not include a trailing backslash or slash on Windows.) See also the section in the help for file.exists on case-insensitive file systems.

The file ‘mode’ follows POSIX conventions, giving three octal digits summarizing the permissions for the file owner, the owner's group and for anyone respectively. Each digit is the logical or of read (4), write (2) and execute/search (1) permissions.

On most systems symbolic links are followed, so information is given about the file to which the link points rather than about the link.

Value

For file.info, data frame with row names the file names and columns

size

double: File size in bytes.

isdir

logical: Is the file a directory?

mode

integer of class "octmode". The file permissions, printed in octal, for example 644.

mtime, ctime, atime

integer of class "POSIXct": file modification, ‘last status change’ and last access times.

uid

integer: the user ID of the file's owner.

gid

integer: the group ID of the file's group.

uname

character: uid interpreted as a user name.

grname

character: gid interpreted as a group name.

Unknown user and group names will be NA.

If extra_cols is false, only the first six columns are returned: as these can all be found from a single C system call this can be faster. (However, properly configured systems will use a ‘name service cache daemon’ to speed up the name lookups.)

Entries for non-existent or non-readable files will be NA. The uid, gid, uname and grname columns may not be supplied on a non-POSIX Unix-alike system, and will not be on Windows.

What is meant by the three file times depends on the OS and file system. On Windows native file systems ctime is the file creation time (something which is not recorded on most Unix-alike file systems). What is meant by ‘file access’ and hence the ‘last access time’ is system-dependent.

The times are reported to an accuracy of seconds, and perhaps more on some systems. However, many file systems only record times in seconds, and some (e.g., modification time on FAT systems) are recorded in increments of 2 or more seconds.

file.mode, file.mtime and file.size are convenience wrappers returning just one of the columns.

Note

Some systems allow files of more than 2Gb to be created but not accessed by the stat system call. Such files will show up as non-readable (and very likely not be readable by any of R's input functions) – fortunately such file systems are becoming rare.

See Also

Sys.readlink to find out about symbolic links, files, file.access, list.files, and DateTimeClasses for the date formats.

Sys.chmod to change permissions.

Examples

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ncol(finf <- file.info(dir()))  # at least six
finf # the whole list
## Those that are more than 100 days old :
finf <- file.info(dir(), extra_cols = FALSE)
finf[difftime(Sys.time(), finf[,"mtime"], units = "days") > 100 , 1:4]

file.info("no-such-file-exists")

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