--- c: Copyright (C) Daniel Stenberg, , et al. SPDX-License-Identifier: curl Long: etag-compare Arg: Help: Pass an ETag from a file as a custom header Protocols: HTTP Added: 7.68.0 Category: http Multi: single See-also: - etag-save - time-cond Example: - --etag-compare etag.txt $URL --- # `--etag-compare` This option makes a conditional HTTP request for the specific ETag read from the given file by sending a custom If-None-Match header using the stored ETag. For correct results, make sure that the specified file contains only a single line with the desired ETag. An empty file is parsed as an empty ETag. Use the option --etag-save to first save the ETag from a response, and then use this option to compare against the saved ETag in a subsequent request.