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FileExists

Function FileExists( const FileName : string) : Boolean

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := FileExists('C:\Fictional\Inbound\order.csv');
end;

Usage​

Use FileExists to make a simple decision based on whether a path currently identifies a file, such as choosing whether to process an optional inbound file. Prefer an absolute path; relative paths depend on the Velox process working directory. Use DirectoryExists when the expected path is a folder.

The result is only a point-in-time check and does not reserve, lock or open the file. For important processing, attempt the real read, move or open operation and handle its failure because the file can change immediately after FileExists returns.

Parameters

NameTypeDescription
FileNamestring, constAbsolute or relative file path to query. Wildcards are not interpreted.

Returns

True when the path resolves to an existing non-directory file; otherwise False.

Additional Technical Info​

FileExists reports whether FileName currently resolves to an existing file that is not a directory. The one-argument script signature does not expose Delphi's FollowLink option, so link following always uses the default True.

The example uses a fictional path. It is source-reviewed and was not executed by the documentation workflow.

Implementation

Velox's wrapper calls installed System.SysUtils.FileExists(FileName) with default FollowLink=True. On Windows, the RTL first inspects attributes. It rejects directory attributes, follows reparse/symbolic-link targets with an opened handle, and uses FindFirstFile as a fallback for selected access, sharing or lock failures so some locked files are still recognised.

Behaviour

  • An accessible ordinary file returns True.
  • A directory, missing path, invalid path or broken followed link returns False.
  • The complete string is a single file path; * and ? are not search patterns.
  • Relative input is resolved from the Velox process current directory.

Edge cases and quirks

  • Scripts cannot request FollowLink=False. A link itself is not treated as the result object; its target is followed, and a directory target returns False.
  • The lock/share fallback means a file can return True even when the next requested access mode cannot open it.
  • Conversely, access, security, remote-share and reparse-point conditions can produce False without proving absence.
  • The result is vulnerable to a time-of-check/time-of-use race. Another actor can replace, remove or lock the path immediately afterward.
  • A relative path depends on process-global state and can be affected by legacy routines such as ProcessPath.

Side effects

No persistent file-system change. The implementation can briefly open or enumerate the path while resolving links and lock/share cases.

Errors

Normal missing, inaccessible, invalid and directory cases return False. Argument conversion and unexpected platform/runtime failures can propagate.

Performance and concurrency

This is normally a metadata query but can perform handle or directory-search fallback operations. Remote paths can block. The function is safe to call concurrently but does not lock the file or make a later operation atomic.

Remarks

Where possible, attempt the real open/read/move operation and handle its result instead of using existence as a precondition. Never use FileExists alone as a security boundary.

Related entries

  • DirectoryExists accepts directories rather than files.
  • FileAge retrieves a successful file's last-write timestamp.
  • FileLocked tests a specific access/lock condition through Velox code.
  • MatchesMask performs lexical wildcard matching; it does not query storage.

External references

Created 2026-07-15