Generate SHA1 checksum of a file

Gets the relative pathname relative to a directory.

In case the two paths are on different file systems, for instance, C:/foo/bar/ and D:/foo/, the method returns pathname as is.

Returns a character string of the relative pathname.

Extract File Information

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

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.

See files For how file paths With marked encodings are interpreted.

File modes are probably only useful On NTFS file systems, And it seems all three digits refer To the file's owner. The execute/search bits are set for directories, and for files based on their extensions (e.g., ‘.exe’, ‘.com’, ‘.cmd’ and ‘.bat’ files). file.access will give a more reliable view of read/write access availability to the R process.

UTF-8-encoded file names Not valid in the current locale can be used.

Junction points And symbolic links are followed, so information Is given about the file/directory To which the link points rather than about the link.

Double: File size In bytes. For missing file, this function will returns a negative number -1; and the file is exists on the filesystem, this function returns ZERO(empty file) or a positive number.

Construct Path to File

Construct the path to a file from components in a platform-independent way.

The implementation is designed to be fast (faster than ‘paste’) as this Function is() used extensively In R itself. It can also be used for environment paths such as 'PATH’ and 'R_LIBS’ with ‘fsep = .Platform$path.sep’. Trailing Path separators are invalid For Windows file paths apart from '/’ and ‘d:/’ (although some functions/utilities do accept them), so a trailing '/’ or ‘\’ is removed there.

A character vector of the arguments concatenated term-by-term and separated by 'fsep’ if all arguments have positive length; otherwise, an empty character vector (unlike 'paste’).

An element Of the result will be marked (see 'Encoding’ as UTF-8 If run In a UTF-8 locale (When marked inputs are converted To UTF-8) Or if an component of the result Is marked as UTF-8, Or as Latin-1 in a non-Latin-1 locale.

Extract File Information

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

a object list with slots:

• DirectoryName: Gets a string representing the directory's full path.
• Length: Gets the size, in bytes, of the current file.
• Name: Gets the name of the file.
• IsReadOnly: Gets or sets a value that determines if the current file is read only.
• Exists: Gets a value indicating whether a file exists.

file.copy works in a similar way to file.append but with the arguments in the natural order for copying. Copying to existing destination files is skipped unless overwrite = TRUE. The to argument can specify a single existing directory. If copy.mode = TRUE file read/write/execute permissions are copied where possible, restricted by ‘umask’. (On Windows this applies only to files. ) Other security attributes such as ACLs are not copied. On a POSIX filesystem the targets of symbolic links will be copied rather than the links themselves, and hard links are copied separately. Using copy.date = TRUE may or may not copy the timestamp exactly (for example, fractional seconds may be omitted), but is more likely to do so as from R 3.4.0.

These functions return a logical vector indicating which operation succeeded for each of the files attempted. Using a missing value for a file or path name will always be regarded as a failure.

Get file extension name

returns a file extension suffix name in lower case, if there is no extension name or path string is empty, then empty string value will be returned.

copy file contents in one dir to another dir

Open an interface to a specific local filesystem location

a directory model

Express File Paths in Canonical Form

Convert file paths to canonical form for the platform, to display them in a user-understandable form and so that relative and absolute paths can be compared.

Return the R Home Directory

Return the R home directory, or the full path to a component of the R installation.

The R home directory is the top-level directory of the R installation being run.

The R home directory Is often referred To As R_HOME, And Is the value Of an environment variable Of that name In an R session. It can be found outside an R session by R RHOME.

dirname returns the part of the path up to but excluding the last path separator, or "." if there is no path separator.

List the Files in a Directory/Folder

List the Files in a Directory/Folder

File Utilities

file_ext returns the file (name) extensions (excluding the leading dot). (Only purely alphanumeric extensions are recognized.)

removes all of the path up to and including the last path separator (if any).

removes all of the invalid character for the windows file name

file.exists returns a logical vector indicating whether the files named by its argument exist. (Here ‘exists’ is in the sense of the system's stat call: a file will be reported as existing only if you have the permissions needed by stat. Existence can also be checked by file.access, which might use different permissions and so obtain a different result. Note that the existence of a file does not imply that it is readable: for that use file.access.) What constitutes a ‘file’ is system-dependent, but should include directories. (However, directory names must not include a trailing backslash or slash on Windows.) Note that if the file is a symbolic link on a Unix-alike, the result indicates if the link points to an actual file, not just if the link exists. Lastly, note the different function exists which checks for existence of R objects.

this function returns FALSE if the given files value is NULL

File Manipulation

These functions provide a low-level interface to the computer's file system.

The ... arguments are concatenated to form one character string: you can specify the files separately or as one vector. All of these functions expand path names: see path.expand. (file.exists silently reports false for paths that would be too long after expansion: the rest will give a warning.)

file.create creates files with the given names if they do Not already exist And truncates them if they do. They are created with the maximal read/write permissions allowed by the 'umask’ setting (where relevant). By default a warning is given (with the reason) if the operation fails.

Case-insensitive file systems

Case-insensitive file systems are the norm on Windows and macOS, but can be found on all OSes (for example a FAT-formatted USB drive is probably case-insensitive).

These functions will most likely match existing files regardless of case on such file systems: however this is an OS function and it is possible that file names might be mapped to upper or lower case.

Symbolic links on Windows

Symbolic links in the sense of POSIX file systems do not exist on Windows: however, NTFS file systems support two similar concepts.

There are ‘junctions’ (or ‘junction points’), unfortunately without a public API: a Windows version of the Unix concept of mounting one directory on another. A junction can link directories located on the same or different local volumes of the same computer, but cannot link to a network drive. Function Sys.junction creates one or more junctions: to should either specify a single existing directory or a set of non-existent file paths of the same length as from. (Command mklink /J can also be used to create junctions.)

A version of symbolic linking to files/directories was implemented more recently, and file.symlink makes use of that interface. However, it has restrictions which are crippling. First, the user needs permission to make symbolic links, and that permission is not normally granted except to Administrator accounts (note: not users with Administrator rights): further many users report that whereas the Policy Editor appears to be able to grant such rights, the API still reports insufficient permissions. Second, the interface needs to know if from is a file or a directory (and it need not yet exist): we have implemented this to allow linking from a directory only if it currently exists.

Care is needed with removing a junction (and most likely also a symbolic link): many tools will remove the target and its contents.

Warning

Always check the return value of these functions when used in package code. This is especially important for file.rename, which has OS-specific restrictions (and note that the session temporary directory is commonly on a different file system from the working directory): it is only portable to use file.rename to change file name(s) within a single directory.

Note

There is no guarantee that these functions will handle Windows relative paths of the form ‘d:path’: try ‘d:./path’ instead. In particular, ‘d:’ is not recognized as a directory. Nor are ‘⁠\\?\⁠’ prefixes (and similar) supported.

Most of these functions accept UTF-8 filepaths not valid in the current locale.

User error in supplying invalid file names (and note that ‘foo/’ and ‘foo\’ are invalid on Windows) has undefined consequences.

These functions return a logical vector indicating which operation succeeded for each of the files attempted. Using a missing value for a file or path name will always be regarded as a failure. If showWarnings = True, file.create will give a warning For an unexpected failure.

dir.create creates the last element of the path, unless recursive = TRUE. Trailing path separators are discarded. On Windows drives are allowed in the path specification and unless the path is rooted, it will be interpreted relative to the current directory on that drive. mode is ignored on Windows.

One of the idiosyncrasies of Windows Is that directory creation may report success but create a directory with a different name, for example dir.create("G.S.") creates '"G.S"’. This is undocumented, and what are the precise circumstances is unknown (and might depend on the version of Windows). Also avoid directory names with a trailing space.

There is no guarantee that these functions will handle Windows relative paths of the form ‘d:path’: try ‘d:./path’ instead. In particular, ‘d:’ is not recognized as a directory. Nor are \\?\ prefixes (and similar) supported.

UTF-8-encoded dirnames Not valid in the current locale can be used.

dir.create and Sys.chmod return invisibly a logical vector indicating if the operation succeeded for each of the files attempted. Using a missing value for a path name will always be regarded as a failure. dir.create indicates failure if the directory already exists. If showWarnings = TRUE, dir.create will give a warning for an unexpected failure (e.g., not for a missing value nor for an already existing component for recursive = TRUE).

dir.exists returns a logical vector of TRUE or FALSE values (without names).

Read Text Lines from a Connection

Read some or all text lines from a connection.

Reads all characters from the current position to the end of the given stream.

Write Lines to a Connection

Write text lines to a connection.

If the con is a character string, the function calls file to obtain a file connection which is opened for the duration of the function call.

If the connection Is open it Is written from its current position. If it Is Not open, it Is opened For the duration Of the Call In "wt" mode And Then closed again.

Normally writeLines Is used With a text-mode connection, And the Default separator Is converted To the normal separator For that platform (LF On Unix/Linux, CRLF On Windows). For more control, open a binary connection And specify the precise value you want written To the file In sep. For even more control, use writeChar On a binary connection.

useBytes Is for expert use. Normally (when false) character strings with marked encodings are converted to the current encoding before being passed to the connection (which might do further re-encoding). useBytes = TRUE suppresses the re-encoding of marked strings so they are passed byte-by-byte to the connection: this can be useful When strings have already been re-encoded by e.g. iconv. (It Is invoked automatically For strings With marked encoding "bytes".)

getwd returns an absolute filepath representing the current working directory of the R process;

setwd(dir) is used to set the working directory to dir.

Save a R# object list in json file format

read list from a given json file

open a *.gz file for make file data read/write

stream object for read/write data

check of the target gz file data is corrupted or not

true for no error in gzfile, false means the given gz file is corrupted

Functions to create, open and close connections, i.e., "generalized files", such as possibly compressed files, URLs, pipes, etc.

• stdin for stdinput stream, and

• stdout for stdoutput stream.

ransfer Binary Data To and From Connections

Read binary data from or write binary data to a connection or raw vector.

close connections, i.e., “generalized files”, such as possibly compressed files, URLs, pipes, etc.

open a zip file

a folder liked list object

decompression of a gzip file and get the deflate file data stream.

create a new buffer object

this function usually works for the http web services.

Create Names for Temporary Files

tempfile returns a vector of character strings which can be used as names for temporary files.

The length of the result is the maximum of the lengths of the three arguments; values of shorter arguments are recycled.

The names are very likely To be unique among calls To tempfile In an R session And across simultaneous R sessions (unless tmpdir Is specified). The filenames are guaranteed Not To be currently In use.

The file name Is made by concatenating the path given by tmpdir, the pattern String, a random String In hex And a suffix Of fileext.

By Default, tmpdir will be the directory given by tempdir(). This will be a subdirectory of the per-session temporary directory found by the following rule when the R session Is started. The environment variables TMPDIR, TMP And TEMP are checked in turn And the first found which points to a writable directory Is used: If none succeeds the value Of R_USER (see Rconsole) Is used. If the path To the directory contains a space In any Of the components, the path returned will use the shortnames version Of the path. Note that setting any Of these environment variables In the R session has no effect On tempdir(): the per-session temporary directory Is created before the interpreter Is started.

a character vector giving the names of possible (temporary) files. Note that no files are generated by tempfile.

Create Names For Temporary Files

• On Windows, both will use a backslash as the path separator.

• On a Unix-alike, the value will be an absolute path (unless tmpdir Is set to a relative path), but it need Not be canonical (see normalizePath) And on macOS it often Is Not.

the path of the per-session temporary directory.

File renames

Delete files or directories

file.remove attempts to remove the files named in its argument. On most Unix platforms ‘file’ includes empty directories, symbolic links, fifos and sockets. On Windows, ‘file’ means a regular file and not, say, an empty directory.

Delete files or directories

this function is the alias name of the function file.remove.

delete all contents in target directory

Check of the given directory path is a system internal directory or not.

The system directories are:

• Windows: c:\, c:/, c:, c:\program files, c:\program files (x86), c:\windows, c:\windows\system32, c:\windows\syswow64
• Linux: /bin, /boot, /dev, /etc, /home, /lib, /lib64, /media, /mnt, /opt, /root, /run, /sbin, /srv, /sys, /usr, /var

read file as data URI string

create a in-memory byte stream object