curl/docs/cmdline-opts/time-cond.d

c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Long: time-cond
Short: z
Arg: <time>
Help: Transfer based on a time condition
Protocols: HTTP FTP
Category: http ftp
Example: -z "Wed 01 Sep 2021 12:18:00" $URL
Example: -z "-Wed 01 Sep 2021 12:18:00" $URL
Example: -z file $URL
Added: 5.8
See-also: etag-compare remote-time
Multi: single
---
Request a file that has been modified later than the given time and date, or
one that has been modified before that time. The <date expression> can be all
sorts of date strings or if it does not match any internal ones, it is taken as
a filename and tries to get the modification date (mtime) from <file>
instead. See the *curl_getdate(3)* man pages for date expression details.

Start the date expression with a dash (-) to make it request for a document
that is older than the given date/time, default is a document that is newer
than the specified date/time.

If provided a non-existing file, curl outputs a warning about that fact and
proceeds to do the transfer without a time condition.