Note: Searching for filenames is always done against FileRun's database and not against the filesystem. For a file to be found, FileRun needs to have it indexed. Indexing is done automatically when browsing folders or performing any task on a folder or a file. A file uploaded via FTP (or any other method other than FileRun) might not appear in the search result if FileRun did not get the opportunity to index it.
Searching by filename is always done in a broad match way. Which means searching for 345 will match all of the following: ab345.pdf, ab345cd.pdf, 345.pdf or 345cd.pdf.
To find only files that start with 345, you would need to search for ^345. It will match 345.pdf and 345cd.pdf.
To find only files that end with 345, you would need to search for 345$. It will match ab345 and 345 but it will not match 345.pdf (because the filename actually ends with .pdf).
To find only an exact match, double-quote the filename, like this "345.pdf".
With Metadata search mode set to Broad match, in FileRun's control panel, searching for 345 will match any of the following values 345, ab345cd, ab345 or 345cd. To find an exact value, use double-quotes: "345".
With Metadata search mode set to Exact match, in FileRun's control panel, searching for 345 will match only 345. To find any value that contains the keyword, use asterisks: *345*.
To find files based on metadata values that start with 345, you would need to search for ^345. It will match both 345 and 345cd.
To find files based on metadata values that end with 345, you would need to search for 345$. It will match both 345 and ab345.
Please see this page for the searching syntax used by ElasticSearch: https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-query-string-query.html#query-string-wildcard