差異處

這裏顯示兩個版本的差異處。

--- linux:shell_script:execution_time_measurement [2016/07/02 11:07]
tony [time command]
+++ linux:shell_script:execution_time_measurement [2023/06/25 09:48] (目前版本)
@@ 行 1: / 行 1: @@
+{{tag>Linux ShellScript}}
 ====== 測量執行時間 ======
 ===== time command =====
@@ 行 12: / 行 13: @@
 </code>
 ===== $SECONDS variable =====
+如果你的對象是script內的一組動作，且不需要精確到毫秒，可以透過SECONDS變數:
+<code bash>
+START=${SECONDS}
+# some operations
+sleep 5
+END=$(($SECONDS - $START))
+echo $END
+</code>
+===== date command =====
+與$SECONDS方法類似，但可以精確到nano second(10^-9)的差距:
+<code bash>
+START=`date +%s%N`
+echo $START
+# some operations
+sleep 1
+END=`date +%s%N`
+echo $END
+END=$(($END - $START))
+echo $END
+# 換算為millisecond
+END=$(($END / 1000000))
+echo $END
+</code>
+output:
+<code bash>
+1467450293336690574
+1467450294338625297
+1001934723
+</code>
+===== Reference =====
+  * [[http://www.livefirelabs.com/unix_tip_trick_shell_script/oct_2003/10272003.htm|Useful Shell Script Variables - Part V - SECONDS]]
+  * [[http://stackoverflow.com/questions/16548528/linux-command-to-get-time-in-milliseconds#comment57307577_16548528|Linux command to get time in milliseconds]]
+=====    =====
+----
+\\
+~~DISQUS~~