blocks|key|1522628|text|如果您坚持从cron运行脚本：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1522629|*+*+*+*+*+/foo/bar/your_script
*+*+*+*+*+sleep+15;+/foo/bar/your_script
*+*+*+*+*+sleep+30;+/foo/bar/your_script
*+*+*+*+*+sleep+45;+/foo/bar/your_script|code-block|syntax|javascript|1522630|并将脚本名称和路径替换为/foo/bar/+your+_script|1522631|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

If you insist of running your script from cron:

<pre><code>* * * * * /foo/bar/your_script
* * * * * sleep 15; /foo/bar/your_script
* * * * * sleep 30; /foo/bar/your_script
* * * * * sleep 45; /foo/bar/your_script
</code></pre>

and replace your script name&amp;path to /foo/bar/your_script

blocks|key|1307713|text|以上内容的修改版本：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1307714|mkdir+/etc/cron.15sec
mkdir+/etc/cron.minute
mkdir+/etc/cron.5minute|code-block|syntax|javascript|1307715|添加到/etc/crontab：|1307716|*+*+*+*+*+root+run-parts+/etc/cron.15sec+>+/dev/null+2>+/dev/null
*+*+*+*+*+root+sleep+15;+run-parts+/etc/cron.15sec+>+/dev/null+2>+/dev/null
*+*+*+*+*+root+sleep+30;+run-parts+/etc/cron.15sec+>+/dev/null+2>+/dev/null
*+*+*+*+*+root+sleep+45;+run-parts+/etc/cron.15sec+>+/dev/null+2>+/dev/null

*+*+*+*+*+root+run-parts+/etc/cron.minute+>+/dev/null+2>+/dev/null
*/5+*+*+*+*+root+run-parts+/etc/cron.5minute+>+/dev/null+2>+/dev/null|1307717|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Modified version of the above:

<pre><code>mkdir /etc/cron.15sec
mkdir /etc/cron.minute
mkdir /etc/cron.5minute
</code></pre>

add to /etc/crontab:

<pre><code>* * * * * root run-parts /etc/cron.15sec &gt; /dev/null 2&gt; /dev/null
* * * * * root sleep 15; run-parts /etc/cron.15sec &gt; /dev/null 2&gt; /dev/null
* * * * * root sleep 30; run-parts /etc/cron.15sec &gt; /dev/null 2&gt; /dev/null
* * * * * root sleep 45; run-parts /etc/cron.15sec &gt; /dev/null 2&gt; /dev/null

* * * * * root run-parts /etc/cron.minute &gt; /dev/null 2&gt; /dev/null
*/5 * * * * root run-parts /etc/cron.5minute &gt; /dev/null 2&gt; /dev/null
</code></pre>

blocks|key|1307556|text|不会在后台运行它吧？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1307557|#!/bin/sh
while+[+1+];+do
++++echo+"Hell+yeah!"+&
++++sleep+15
done|code-block|syntax|javascript|1307558|这几乎是它得到的最高效率。重要的部分仅每15秒执行一次，脚本在其余时间休眠(因此不会浪费周期)。|1307559|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Won't running this in the background do it?

<pre><code>#!/bin/sh
while [ 1 ]; do
 echo "Hell yeah!" &amp;
 sleep 15
done
</code></pre>

This is about as efficient as it gets. The important part only gets executed every 15 seconds and the script sleeps the rest of the time (thus not wasting cycles).

blocks|key|1522872|text|我写了一个比cron更快的调度器。我还实现了一个重叠的保护。如果上一个进程仍在运行，您可以将调度程序配置为不启动新进程。看一看https://github.com/sioux1977/scheduler/wiki|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1522873|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/sioux1977/scheduler/wiki^0|1R|17|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

I wrote a scheduler faster than cron. I have also implemented an overlapping guard. You can configure the scheduler to not start new process if previous one is still running. Take a look at <a href="https://github.com/sioux1977/scheduler/wiki" rel="nofollow">https://github.com/sioux1977/scheduler/wiki</a>

blocks|key|1307618|text|使用nanosleep(2)。它使用结构timespec，用于指定精确到纳秒的时间间隔。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1307619|struct+timespec+{
+++++++++++time_t+tv_sec;++++++++/*+seconds+*/
+++++++++++long+++tv_nsec;+++++++/*+nanoseconds+*/
+++++++};|code-block|syntax|javascript|1307620|entityMap|0|LINK|mutability|MUTABLE|url|http://kernel.org/doc/man-pages/online/pages/man2/nanosleep.2.html^0|K|8|2|C|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@$9|V|A|W|1|X]]|E|$]]|$1|F|3|G|5|H|7|Y|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Z|8|@]|D|@]|E|$]]]|L|$M|$5|N|O|P|E|$Q|R]]]]

Use <a href="http://kernel.org/doc/man-pages/online/pages/man2/nanosleep.2.html" rel="nofollow">nanosleep(2)</a>. It uses structure <code>timespec</code> that is used to specify intervals of time with nanosecond precision.

<pre><code>struct timespec {
 time_t tv_sec; /* seconds */
 long tv_nsec; /* nanoseconds */
 };
</code></pre>

blocks|key|1307721|text|#!+/bin/sh

#+Run+all+programs+in+a+directory+in+parallel
#+Usage:+run-parallel+directory+delay
#+Copyright+2013+by+Marc+Perkel
#+docs+at+http://wiki.junkemailfilter.com/index.php/How_to_run_a_Linux_script_every_few_seconds_under_cron"
#+Free+to+use+with+attribution

if+[+$#+-eq+0+]
then
+++echo
+++echo+"run-parallel+by+Marc+Perkel"
+++echo
+++echo+"This+program+is+used+to+run+all+programs+in+a+directory+in+parallel"+
+++echo+"or+to+rerun+them+every+X+seconds+for+one+minute."
+++echo+"Think+of+this+program+as+cron+with+seconds+resolution."
+++echo
+++echo+"Usage:+run-parallel+[directory]+[delay]"
+++echo
+++echo+"Examples:"
+++echo+"+++run-parallel+/etc/cron.20sec+20"
+++echo+"+++run-parallel+20"
+++echo+"+++#+Runs+all+executable+files+in+/etc/cron.20sec+every+20+seconds+or+3+times+a+minute."
+++echo+
+++echo+"If+delay+parameter+is+missing+it+runs+everything+once+and+exits."
+++echo+"If+only+delay+is+passed+then+the+directory+/etc/cron.[delay]sec+is+assumed."
+++echo
+++echo+'if+"cronsec"+is+passed+then+it+runs+all+of+these+delays+2+3+4+5+6+10+12+15+20+30'
+++echo+"resulting+in+30+20+15+12+10+6+5+4+3+2+executions+per+minute."+
+++echo
+++exit
fi

#+If+"cronsec"+is+passed+as+a+parameter+then+run+all+the+delays+in+parallel

if+[+$1+=+cronsec+]
then
+++$0+2+&
+++$0+3+&
+++$0+4+&
+++$0+5+&
+++$0+6+&
+++$0+10+&
+++$0+12+&
+++$0+15+&
+++$0+20+&
+++$0+30+&
+++exit
fi

#+Set+the+directory+to+first+prameter+and+delay+to+second+parameter

dir=$1
delay=$2

#+If+only+parameter+is+2,3,4,5,6,10,12,15,20,30+then+automatically+calculate+
#+the+standard+directory+name+/etc/cron.[delay]sec

if+[[+"$1"+=~+%5E(2%7C3%7C4%7C5%7C6%7C10%7C12%7C15%7C20%7C30)$+]]
then
+++dir="/etc/cron.$1sec"
+++delay=$1
fi

#+Exit+if+directory+doesn't+exist+or+has+no+files

if+[+!+"$(ls+-A+$dir/)"+]
then
+++exit
fi

#+Sleep+if+both+$delay+and+$counter+are+set

if+[+!+-z+$delay+]+&&+[+!+-z+$counter+]
then
+++sleep+$delay
fi

#+Set+counter+to+0+if+not+set

if+[+-z+$counter+]
then
+++counter=0
fi

#+Run+all+the+programs+in+the+directory+in+parallel
#+Use+of+timeout+ensures+that+the+processes+are+killed+if+they+run+too+long

for+program+in+$dir/*+;+do
+++if+[+-x+$program+]+
+++then
++++++if+[+"0$delay"+-gt+1+]+
++++++then
+++++++++timeout+$delay+$program+&>+/dev/null+&
++++++else
+++++++++$program+&>+/dev/null+&
++++++fi
+++fi
done

#+If+delay+not+set+then+we're+done

if+[+-z+$delay+]
then
+++exit
fi

#+Add+delay+to+counter

counter=$((+$counter+%2B+$delay+))

#+If+minute+is+not+up+-+call+self+recursively

if+[+$counter+-lt+60+]
then
+++.+$0+$dir+$delay+&
fi

#+Otherwise+we're+done|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1307722|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>#! /bin/sh

# Run all programs in a directory in parallel
# Usage: run-parallel directory delay
# Copyright 2013 by Marc Perkel
# docs at http://wiki.junkemailfilter.com/index.php/How_to_run_a_Linux_script_every_few_seconds_under_cron"
# Free to use with attribution

if [ $# -eq 0 ]
then
 echo
 echo "run-parallel by Marc Perkel"
 echo
 echo "This program is used to run all programs in a directory in parallel" 
 echo "or to rerun them every X seconds for one minute."
 echo "Think of this program as cron with seconds resolution."
 echo
 echo "Usage: run-parallel [directory] [delay]"
 echo
 echo "Examples:"
 echo " run-parallel /etc/cron.20sec 20"
 echo " run-parallel 20"
 echo " # Runs all executable files in /etc/cron.20sec every 20 seconds or 3 times a minute."
 echo 
 echo "If delay parameter is missing it runs everything once and exits."
 echo "If only delay is passed then the directory /etc/cron.[delay]sec is assumed."
 echo
 echo 'if "cronsec" is passed then it runs all of these delays 2 3 4 5 6 10 12 15 20 30'
 echo "resulting in 30 20 15 12 10 6 5 4 3 2 executions per minute." 
 echo
 exit
fi

# If "cronsec" is passed as a parameter then run all the delays in parallel

if [ $1 = cronsec ]
then
 $0 2 &amp;
 $0 3 &amp;
 $0 4 &amp;
 $0 5 &amp;
 $0 6 &amp;
 $0 10 &amp;
 $0 12 &amp;
 $0 15 &amp;
 $0 20 &amp;
 $0 30 &amp;
 exit
fi

# Set the directory to first prameter and delay to second parameter

dir=$1
delay=$2

# If only parameter is 2,3,4,5,6,10,12,15,20,30 then automatically calculate 
# the standard directory name /etc/cron.[delay]sec

if [[ "$1" =~ ^(2|3|4|5|6|10|12|15|20|30)$ ]]
then
 dir="/etc/cron.$1sec"
 delay=$1
fi

# Exit if directory doesn't exist or has no files

if [ ! "$(ls -A $dir/)" ]
then
 exit
fi

# Sleep if both $delay and $counter are set

if [ ! -z $delay ] &amp;&amp; [ ! -z $counter ]
then
 sleep $delay
fi

# Set counter to 0 if not set

if [ -z $counter ]
then
 counter=0
fi

# Run all the programs in the directory in parallel
# Use of timeout ensures that the processes are killed if they run too long

for program in $dir/* ; do
 if [ -x $program ] 
 then
 if [ "0$delay" -gt 1 ] 
 then
 timeout $delay $program &amp;&gt; /dev/null &amp;
 else
 $program &amp;&gt; /dev/null &amp;
 fi
 fi
done

# If delay not set then we're done

if [ -z $delay ]
then
 exit
fi

# Add delay to counter

counter=$(( $counter + $delay ))

# If minute is not up - call self recursively

if [ $counter -lt 60 ]
then
 . $0 $dir $delay &amp;
fi

# Otherwise we're done
</code></pre>

blocks|key|1522807|text|由于我之前的回答，我想出了另一个不同的解决方案，也许更好。这段代码允许进程以微秒级的精度每分钟运行60次以上。你需要usleep程序来完成这项工作。应该是好到每秒50次。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1522808|#!+/bin/sh

#+Microsecond+Cron
#+Usage:+cron-ms+start
#+Copyright+2014+by+Marc+Perkel
#+docs+at+http://wiki.junkemailfilter.com/index.php/How_to_run_a_Linux_script_every_few_seconds_under_cron"
#+Free+to+use+with+attribution

basedir=/etc/cron-ms

if+[+$#+-eq+0+]
then
+++echo
+++echo+"cron-ms+by+Marc+Perkel"
+++echo
+++echo+"This+program+is+used+to+run+all+programs+in+a+directory+in+parallel+every+X+times+per+minute."
+++echo+"Think+of+this+program+as+cron+with+microseconds+resolution."
+++echo
+++echo+"Usage:+cron-ms+start"
+++echo
+++echo+"The+scheduling+is+done+by+creating+directories+with+the+number+of"
+++echo+"executions+per+minute+as+part+of+the+directory+name."
+++echo
+++echo+"Examples:"
+++echo+"++/etc/cron-ms/7++++++#+Executes+everything+in+that+directory++7+times+a+minute"
+++echo+"++/etc/cron-ms/30+++++#+Executes+everything+in+that+directory+30+times+a+minute"
+++echo+"++/etc/cron-ms/600++++#+Executes+everything+in+that+directory+10+times+a+second"
+++echo+"++/etc/cron-ms/2400+++#+Executes+everything+in+that+directory+40+times+a+second"
+++echo
+++exit
fi

#+If+"start"+is+passed+as+a+parameter+then+run+all+the+loops+in+parallel
#+The+number+of+the+directory+is+the+number+of+executions+per+minute
#+Since+cron+isn't+accurate+we+need+to+start+at+top+of+next+minute

if+[+$1+=+start+]
then
+++for+dir+in+$basedir/*+;+do
++++++$0+${dir##*/}+60000000+&
+++done
+++exit
fi

#+Loops+per+minute+and+the+next+interval+are+passed+on+the+command+line+with+each+loop

loops=$1
next_interval=$2

#+Sleeps+until+a+specific+part+of+a+minute+with+microsecond+resolution.+60000000+is+full+minute

usleep+$((+$next_interval+-+10#$(date+%2B%25S%25N)+/+1000+))

#+Run+all+the+programs+in+the+directory+in+parallel

for+program+in+$basedir/$loops/*+;+do
+++if+[+-x+$program+]+
+++then
++++++$program+&>+/dev/null+&
+++fi
done

#+Calculate+next_interval

next_interval=$(($next_interval+%25+60000000+%2B+(60000000+/+$loops)+))

#+If+minute+is+not+up+-+call+self+recursively

if+[+$next_interval+-lt+$((+60000000+/+$loops+*+$loops))+]
then
+++.+$0+$loops+$next_interval+&
fi

#+Otherwise+we're+done|code-block|syntax|javascript|1522809|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Since my previous answer I came up with another solution that is different and perhaps better. This code allows processes to be run more than 60 times a minute with microsecond precision. You need the usleep program to make this work. Should be good to up to 50 times a second.

<pre><code>#! /bin/sh

# Microsecond Cron
# Usage: cron-ms start
# Copyright 2014 by Marc Perkel
# docs at http://wiki.junkemailfilter.com/index.php/How_to_run_a_Linux_script_every_few_seconds_under_cron"
# Free to use with attribution

basedir=/etc/cron-ms

if [ $# -eq 0 ]
then
 echo
 echo "cron-ms by Marc Perkel"
 echo
 echo "This program is used to run all programs in a directory in parallel every X times per minute."
 echo "Think of this program as cron with microseconds resolution."
 echo
 echo "Usage: cron-ms start"
 echo
 echo "The scheduling is done by creating directories with the number of"
 echo "executions per minute as part of the directory name."
 echo
 echo "Examples:"
 echo " /etc/cron-ms/7 # Executes everything in that directory 7 times a minute"
 echo " /etc/cron-ms/30 # Executes everything in that directory 30 times a minute"
 echo " /etc/cron-ms/600 # Executes everything in that directory 10 times a second"
 echo " /etc/cron-ms/2400 # Executes everything in that directory 40 times a second"
 echo
 exit
fi

# If "start" is passed as a parameter then run all the loops in parallel
# The number of the directory is the number of executions per minute
# Since cron isn't accurate we need to start at top of next minute

if [ $1 = start ]
then
 for dir in $basedir/* ; do
 $0 ${dir##*/} 60000000 &amp;
 done
 exit
fi

# Loops per minute and the next interval are passed on the command line with each loop

loops=$1
next_interval=$2

# Sleeps until a specific part of a minute with microsecond resolution. 60000000 is full minute

usleep $(( $next_interval - 10#$(date +%S%N) / 1000 ))

# Run all the programs in the directory in parallel

for program in $basedir/$loops/* ; do
 if [ -x $program ] 
 then
 $program &amp;&gt; /dev/null &amp;
 fi
done

# Calculate next_interval

next_interval=$(($next_interval % 60000000 + (60000000 / $loops) ))

# If minute is not up - call self recursively

if [ $next_interval -lt $(( 60000000 / $loops * $loops)) ]
then
 . $0 $loops $next_interval &amp;
fi

# Otherwise we're done
</code></pre>

blocks|key|1522720|text|为了避免可能的执行重叠，请使用该thread中描述的锁定机制。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1522721|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/5428631/php-preventing-collision-in-cron-file-lock-safe^0|G|6|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

To avoid possible overlapping of execution, use a locking mechanism as described in that <a href="https://stackoverflow.com/questions/5428631/php-preventing-collision-in-cron-file-lock-safe">thread</a>.

I've seen a few solutions, including watch and simply running a looping (and sleeping) script in the background, but nothing has been ideal.

I have a script that needs to run every 15 seconds, and since cron won't support seconds, I'm left to figuring out something else.

What's the most robust and efficient way to run a script every 15 seconds on unix? The script needs to also run after a reboot.

How to get a unix script to run every 15 seconds?

我已经看到了一些解决方案，包括手表和简单地在后台运行循环(和睡眠)脚本，但没有一个是理想的。我有一个需要每隔15秒运行一次的脚本，由于cron不支持秒，所以我只能解决其他问题。在unix上，每15秒运行一次脚本的最健壮和最有效的方法是什么？该脚本还需要在重新启动后运行。

问如何让unix脚本每15秒运行一次？
EN

回答 8

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问如何让unix脚本每15秒运行一次？EN

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问如何让unix脚本每15秒运行一次？
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