.tmp extension when the download process is interrupted, canceled, or fails before completion. To resolve this issue and retrieve your actual data, you must first locate these incomplete files in your working directory. Once identified, you can either resume the interrupted transfer using specific flags or delete the corrupted artifacts to start a fresh download. This behavior is standard for robust download managers that prioritize data integrity over speed, ensuring that partial downloads do not overwrite existing valid files.
Understanding Wget's Temporary File Behavior
When you initiate a download withwget, it does not write directly to the final filename immediately. Instead, it writes to a temporary file (often named filename.part or filename.tmp) and renames it only upon successful completion. This mechanism prevents data corruption if the network connection drops unexpectedly. If you see .tmp files remaining after a session, it indicates that the transfer did not finish cleanly. This is particularly common when downloading large datasets, such as high-resolution satellite imagery from NASA's LAADS DAAC archive, where network stability can be variable over long periods.
The presence of these files is not an error in itself but a signal that the previous attempt was incomplete. It is crucial to understand that deleting these files without resuming the download will result in losing any partially downloaded data. Therefore, the solution involves either cleaning up stale files from old sessions or configuring wget to handle interruptions more gracefully.
Resuming Interrupted Downloads
The most effective way to deal with.tmp files is to use the resume feature. If you are downloading a large file and the connection drops, wget saves the progress in a temporary file. You can restart the download by adding the -c flag, which stands for "continue." This tells wget to check the size of the remote file and the local temporary file, then request the missing bytes from the server.
For example, if you were downloading a satellite image named MODIS_image.hdf, and the download failed, leaving a MODIS_image.hdf.tmp or MODIS_image.hdf.part file, you would run:
wget -c https://example.com/path/to/MODIS_image.hdf.tmp suffix. This method is essential for large scientific datasets where re-downloading from the beginning would waste significant bandwidth and time.
Cleaning Up Stale Temporary Files
If the temporary files are from previous failed attempts that cannot be resumed, or if you simply want a clean directory, you need to remove them manually. Be cautious when deleting these files, as they may contain valuable partial data. Always verify that you do not need the partial content before deletion. You can identify these files by looking for extensions like.tmp, .part, or sometimes no extension if the naming convention differs. To remove all temporary files in the current directory, you can use the rm command with a glob pattern:
rm *.tmp
rm *.partConfiguring Wget for Better Stability
To reduce the frequency of encountering stuck.tmp files, you can adjust wget's configuration options. Increasing the timeout values can help prevent premature disconnections during slow phases of the download. Additionally, enabling retry logic ensures that wget automatically attempts to reconnect if the network fails briefly.
You can set these options in your .wgetrc file or pass them directly in the command line. For instance, setting a longer timeout and increasing retries looks like this:
wget --timeout=60 --tries=10 https://example.com/large_file.hdfAlternative Download Managers
In some cases, wget may not be the best tool for every scenario. If you frequently encounter issues with large file transfers, consider using alternative download managers that offer more advanced features like multi-threading or better error handling. Tools likecurl or graphical downloaders might provide a smoother experience for certain types of data transfers. However, for automated scripts and command-line workflows, wget remains a reliable choice when configured correctly.
It is also worth noting that some servers may not support resuming downloads. In such cases, the -c flag will fail, and you will need to delete the temporary file and start over. Always check the server's capabilities if you suspect that resumption is not supported.
Frequently Asked Questions
Why does wget create .tmp files instead of the final file?
Wget uses temporary files to ensure data integrity during the download process. It only renames the file to its final name once the entire transfer is verified as complete. This prevents partial or corrupted files from being saved to disk.
How can I resume a download that stopped at a .tmp file?
You can resume the download by running the wget command again with the -c flag. Wget will detect the existing temporary file and continue downloading from where it left off, provided the server supports resumption.
Is it safe to delete .tmp files created by wget?
Yes, it is safe to delete .tmp files if you do not need the partial data. However, if you intend to resume the download later, deleting the file will force you to start the download from scratch.
What should I do if wget -c fails to resume?
If the -c flag fails, the server likely does not support resuming downloads. In this case, you must delete the temporary file and start a new download from the beginning. Check the server documentation to confirm its capabilities.
Can I configure wget to automatically remove temporary files on failure?
Wget does not have a built-in option to automatically delete temporary files upon failure. You must manually remove them or write a script to clean up stale files periodically. Some users prefer to use other tools that offer more granular control over temporary file management.