Append to File

Append to File

Type: append-file  ·  Package: Filesystem Activities v1.0.6  ·  Output: string

Appends text to the end of a file without erasing what is already there. If the file does not exist, it creates it. It is the ideal activity for building logs or accumulating lines over one run (or several).

How it works

Appends content to the end of the file at path.

• Line break: with newLine = true (default) and an existing file, it puts a Windows line break (\r\n) before the content, so each call lands on its own line. If the file did not exist, it writes the content with no leading break. It never adds a break at the end.
• Folders: if the file’s folder does not exist, it is created (with any intermediate ones).
• Encoding: with utf-8 (default), a new file starts with the UTF-8 BOM. Use the same encoding for every call on the same file. See encoding.
• Not idempotent: each run appends the text again. If you retry it with Retry, the line may end up duplicated.

Required parameters

Parameter	Type	Default	Description
path	string	—	File path, including its folder (absolute or with asset(...)).
content	string	—	Text to append. If the expression is null, no text is appended (the line break still is, when it applies).

Optional parameters

Parameter	Type	Default	Description
encoding	string	"utf-8"	File encoding: utf-8, iso-8859-1, utf-16, utf-32, us-ascii… See encoding.
newLine	bool	true	Puts a line break before the content when the file already exists.

Output

Returns a string with the file path (as you gave it in path), in case you want to use it in a later activity.

Common errors

Message	Cause and fix
The process cannot access the file '…' because it is being used by another process.	The file is open in another program. Close it or use a different file.
Access to the path '…' is denied.	No write permission on the folder, or the file is read-only.
'windows-1252' is not a supported encoding name…	The encoding is not available. Use iso-8859-1 or utf-8.
'path' is required.	The path expression evaluated to null.

If path is just a file name, it is written to the robot’s working folder (since version 1.0.6; before, the activity failed). Use a full path so you always know where the file ends up.

Example

Log each processed item to a file and show its content at the end:

For Each   items = invoices   itemVariable = invoice
 └─ activities:
      ... process ...
      Append to File   path = "C:/logs/processed.txt"   content = invoice.number + " — OK"   → output: logPath

Read File   path = logPath   → output: summary
Log   message = "Processed: " + summary

Append vs Write

• Append to File: adds to the end and keeps what was there. For logs and history.
• Write File: replaces the whole content. To produce a file from scratch.

Related activities

• Write File — create or replace the whole file.
• Read File — read the accumulated content.