PutAppend (>>>)

expr>>>filename
appends expr to a file.

PutAppend[expr₁, expr₂, ..., "filename"]
appends a sequence of expressions expr_i to a file.

PutAppend works the same as Put, except that it adds output to the end of the file, rather than replacing the complete contents of the file.

Append expression values at the end of a temporary file:

Set the directory to one for temporary files:

Put the value of x in a file:

Update x and append the new value to the file:

The file now contains the two values:

Append successive iterates to the file in a loop:

Reset to the original directory:

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