How to prevent overwriting existing files with wget

Repeated downloads need an explicit local-file policy when the same URL is fetched again later. Without one, a rerun either creates extra numbered copies that clutter the directory or writes again to a fixed path that another job expects to stay stable.

For ordinary single-file downloads, GNU wget already avoids clobbering the original local filename by saving the next copy as file.1, file.2, and so on. --no-clobber (-nc) changes that behavior by refusing to retrieve the file again, while --timestamping (-N) keeps the original filename and downloads only when the server copy is newer or sized differently. The current GNU Wget manual also notes that -nc cannot be combined with -N.

A fixed destination set with --output-document (-O) follows different rules because wget writes to one exact pathname instead of creating numbered siblings. Use that form only when one stable local filename is required, because plain -O writes the target file again on later runs, -N warns that it does nothing with -O, and -nc with -O only skips the transfer after that fixed file already exists.

1. Download the file once so there is a local copy to protect.

   $ wget https://downloads.example.net/exports/2026-04/daily-settlement-2026-04-22.csv
   --2026-04-22 11:18:03--  https://downloads.example.net/exports/2026-04/daily-settlement-2026-04-22.csv
   Resolving downloads.example.net (downloads.example.net)... 203.0.113.50
   Connecting to downloads.example.net (downloads.example.net)|203.0.113.50|:443... connected.
   HTTP request sent, awaiting response... 200 OK
   Length: 65536 (64K) [text/csv]
   Saving to: 'daily-settlement-2026-04-22.csv'
   
   ##### snipped #####
   2026-04-22 11:18:03 (56.3 MB/s) - 'daily-settlement-2026-04-22.csv' saved [65536/65536]

2. Repeat the same command once to see the default numbered-copy behavior.

   $ wget https://downloads.example.net/exports/2026-04/daily-settlement-2026-04-22.csv
   --2026-04-22 11:18:10--  https://downloads.example.net/exports/2026-04/daily-settlement-2026-04-22.csv
   Resolving downloads.example.net (downloads.example.net)... 203.0.113.50
   Connecting to downloads.example.net (downloads.example.net)|203.0.113.50|:443... connected.
   HTTP request sent, awaiting response... 200 OK
   Length: 65536 (64K) [text/csv]
   Saving to: 'daily-settlement-2026-04-22.csv.1'
   
   ##### snipped #####
   2026-04-22 11:18:10 (57.1 MB/s) - 'daily-settlement-2026-04-22.csv.1' saved [65536/65536]

   For a normal single-file download, the numbered sibling is the default protection against overwriting the original local file.

3. Use --no-clobber when a rerun should be skipped instead of saved as another sibling file.

   $ wget --no-clobber https://downloads.example.net/exports/2026-04/daily-settlement-2026-04-22.csv
   File 'daily-settlement-2026-04-22.csv' already there; not retrieving.

   -nc suppresses the automatic .1, .2, and .3 copies for that destination name.

4. Use --timestamping when the same filename should be refreshed only after the server copy changes.

   $ wget --timestamping https://downloads.example.net/exports/2026-04/daily-settlement-2026-04-22.csv
   --2026-04-22 11:18:18--  https://downloads.example.net/exports/2026-04/daily-settlement-2026-04-22.csv
   Resolving downloads.example.net (downloads.example.net)... 203.0.113.50
   Connecting to downloads.example.net (downloads.example.net)|203.0.113.50|:443... connected.
   HTTP request sent, awaiting response... 304 Not Modified
   File 'daily-settlement-2026-04-22.csv' not modified on server. Omitting download.

   -N is the better fit when unchanged files should be skipped but a newer remote copy should still replace the local file.

5. Guard a fixed output filename separately when the job must always use one exact local path.

   $ wget --no-clobber --output-document=daily-settlement-current.csv https://downloads.example.net/exports/2026-04/daily-settlement-2026-04-22.csv
   File 'daily-settlement-current.csv' already there; not retrieving.

   -O points to one exact pathname instead of the normal server-derived filename, so plain -O writes that file again on later runs and -N warns that it does nothing in combination with -O.

6. Verify the resulting filenames before another script consumes the directory.

   $ ls -1
   daily-settlement-2026-04-22.csv
   daily-settlement-2026-04-22.csv.1
   daily-settlement-current.csv

   The final listing shows the difference between the three policies: default numbered copy, explicit skip on rerun, and one separately managed fixed output filename.