etag-save.md (942B)
1 --- 2 c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al. 3 SPDX-License-Identifier: curl 4 Long: etag-save 5 Arg: <file> 6 Help: Parse incoming ETag and save to a file 7 Protocols: HTTP 8 Added: 7.68.0 9 Category: http 10 Multi: single 11 See-also: 12 - etag-compare 13 Example: 14 - --etag-save storetag.txt $URL 15 --- 16 17 # `--etag-save` 18 19 Save an HTTP ETag to the specified file. An ETag is a caching related header, 20 usually returned in a response. Use this option with a single URL only. 21 22 If no ETag is sent by the server, an empty file is created. 23 24 In many situations you want to use an existing etag in the request to avoid 25 downloading the same resource again but also save the new etag if it has 26 indeed changed, by using both etag options --etag-save and --etag-compare with 27 the same filename, in the same command line. 28 29 Starting in curl 8.12.0, using the --create-dirs option can also create 30 missing directory components for the path provided in --etag-save.