So far I couldn't find anything really, but is it true that curl doesn't really time out at all?
user@host:~# curl http://localhost/testdir/image.jpg
I'm asking because I'm redirecting any request for images in testdir to a separate Apache module which generates those pictures on the fly. It can take up to 15 minutes before the picture is actually ready and delivered to the requesting client.
Will curl always wait (or is it depending on configuration) or is there any sort of timeout?
Yes.
curl has two options: --connect-timeout and --max-time.
Quoting from the manpage:
--connect-timeout <seconds>
Maximum time in seconds that you allow the connection to the
server to take. This only limits the connection phase, once
curl has connected this option is of no more use. Since 7.32.0,
this option accepts decimal values, but the actual timeout will
decrease in accuracy as the specified timeout increases in deci‐
mal precision. See also the -m, --max-time option.
If this option is used several times, the last one will be used.
and:
-m, --max-time <seconds>
Maximum time in seconds that you allow the whole operation to
take. This is useful for preventing your batch jobs from hang‐
ing for hours due to slow networks or links going down. Since
7.32.0, this option accepts decimal values, but the actual time‐
out will decrease in accuracy as the specified timeout increases
in decimal precision. See also the --connect-timeout option.
If this option is used several times, the last one will be used.
Here (on Debian) it stops trying to connect after 2 minutes, regardless of the time specified with --connect-timeout and although the default connect timeout value seems to be 5 minutes according to the DEFAULT_CONNECT_TIMEOUT macro in lib/connect.h.
A default value for --max-time doesn't seem to exist, making curl wait forever for a response if the initial connect succeeds.
You are probably interested in the latter option, --max-time. For your case set it to 900 (15 minutes).
Specifying option --connect-timeout to something like 60 (one minute) might also be a good idea. Otherwise curl will try to connect again and again, apparently using some backoff algorithm.
--max-time 900, curl still exits after 2 min
– kirill_igum
Dec 29 '20 at 08:12
There is timelimit: /usr/bin/timelimit - effectively limit the absolute execution time of a process
Options:
-p If the child process is terminated by a signal, timelimit
propagates this condition, i.e. sends the same signal to itself.
This allows the program executing timelimit to determine
whether the child process was terminated by a signal or
actually exited with an exit code larger than 128.
-q Quiet operation - timelimit does not output diagnostic
messages about signals sent to the child process.
-S killsig
Specify the number of the signal to be sent to the
process killtime seconds after warntime has expired.
Defaults to 9 (SIGKILL).
-s warnsig
Specify the number of the signal to be sent to the
process warntime seconds after it has been started.
Defaults to 15 (SIGTERM).
-T killtime
Specify the maximum execution time of the process before
sending killsig after warnsig has been sent. Defaults to 120 seconds.
-t warntime
Specify the maximum execution time of the process in
seconds before sending warnsig. Defaults to 3600 seconds.
On systems that support the setitimer(2) system call, the
warntime and killtime values may be specified in fractional
seconds with microsecond precision.
timeout command. but when i ran timeout 900 curl https://..., it exited after 2 minutes not 15
– kirill_igum
Dec 29 '20 at 08:10
Better than --max-time are the --speed-limit and --speed-time options. In short, --speed-limit specifies the minimum average speed which you are willing to accept, and --speed-time specifies how long the transfer speed can remain below that limit before the transfer times out and is aborted.
If you have coreutils installed on MacOS you can use the GNU timeout command which is included with that package. The GNU tools are all prefixed with a g so the CLI would be gtimeout.
gtimeout --help
Usage: gtimeout [OPTION] DURATION COMMAND [ARG]...
or: gtimeout [OPTION]
Start COMMAND, and kill it if still running after DURATION.
$ gtimeout 1s curl -I http://www.google.com/
HTTP/1.1 200 OK
Date: Wed, 31 Oct 2018 03:36:08 GMT
Expires: -1
Cache-Control: private, max-age=0
Content-Type: text/html; charset=ISO-8859-1
P3P: CP="This is not a P3P policy! See g.co/p3phelp for more info."
Server: gws
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Set-Cookie: 1P_JAR=2018-10-31-03; expires=Fri, 30-Nov-2018 03:36:08 GMT; path=/; domain=.google.com
HttpOnly
Transfer-Encoding: chunked
Accept-Ranges: none
Vary: Accept-Encoding
Couple of solutions in BASH4+
# -- server available to check via port xxx ? --
function isServerAvailableNC() {
max_secs_run="${3}"
if timeout $max_secs_run nc -z ${1} ${2} 2>/dev/null >/dev/null; then
#echo "${1} ✓"
true
else
#echo "${1} ✗"
return
fi
}
# -- server available to check via port xxx ? --
# -- supported protocols (HTTP, HTTPS, FTP, FTPS, SCP, SFTP, TFTP, DICT, TELNET, LDAP or FILE) --
#/usr/bin/curl -sSf --max-time 3 https://ifwewanted.to.confirm.https.com/ --insecure
function isServerAvailableCURL() {
max_secs_run="${3}"
proto="http://"
if [ ! -z ${2} ] || [ ${2} -gt 80 ] ;then
proto="https://"
fi
if /usr/bin/curl -sSf --max-time "${max_secs_run}" "${1}" --insecure 2>/dev/null >/dev/null; then
#echo "${1} ✓"
true
else
#echo "${1} ✗"
false
fi
}
Sample use:
RECOMMEND THAT NC used if we need a specific port
host="1.2.3.4"
if isServerAvailableCURL "$host" "80" "3";then
check_remote_domain_cert "$host"
fi
host="1.2.3.4"
if isServerAvailableNC "$host" "80" "3";then
check_remote_domain_cert "$host"
fi
