Module OS.File

File operations.

Famous file paths

val null : fpath

null represents a file on the OS that discards all writes and returns end of file on reads.

val dash : fpath

dash is "-". This value is is used by read and write to respectively denote stdin and stdout.

Existence and deletion

val exists : fpath -> bool result

exists file is true if file is a regular in the file system and false otherwise. Symbolic links are followed.

val must_exist : fpath -> fpath result

must_exist file is file if file is a regular file in the file system and an error otherwise. Symbolic links are followed.

val delete : ?⁠must_exist:bool -> fpath -> unit result

delete ~must_exist file deletes file file. If must_exist is true (defaults to false) an error is returned if file doesn't exist.

Folding over file hierarchies

val fold : ?⁠skip:(fpath -> bool) -> (fpath -> 'a -> 'a) -> 'a -> fpath list -> 'a result

fold_files skip f acc paths folds f over the files found in the file hierarchies starting at paths. Files and directories p for which skip p is true are skipped. skip defaults to (fun _ -> false).

Reading and writing

val read : fpath -> string result

read file is file's contents. If file is dash reads from stdin and the channel is not closed when the function returns.

val write : fpath -> string -> unit result

write file content writes content to file. If file is dash writes to stdout and flushes but doesn't close the channel when the function returns.

val write_subst : fpath -> (string * string) list -> string -> unit result

write_subst file vars content is like write except any occurence of a string of the form "%%ID%%" in content is replaced by the value of List.assoc "ID" vars, if any.

Temporary files

val tmp : unit -> fpath result

tmp () creates a temporary file and returns its name. The file is destroyed at the end of program execution.