Sleep

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Sleep random seconds in programming

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MS-DOS on Windows[edit]

Approach 1: %RANDOM% + ping local[edit]

Purpose

  • Sleep random seconds between 5 ~ 60 seconds

BAT file:

REM print current date & time
ECHO %date% %time%

REM sleep 5 ~ 60 seconds
SET /a timeout=%RANDOM% * 55 / 32767 + 5
ping 127.0.0.1 -n %timeout% > nul

REM print current date & time
ECHO %date% %time%

Instruction[1]

  • %RANDOM% returns an integer between 0 and 32767[2].
  • 55 is the range of values you want: 5 to 60.
  • 32767 is the range of values returned by %RANDOM% (0 to 32767).
  • 5 is the minimum value you want. The original range of values is '0 to 55'. After plus 5 the range became '5 ~ 65'.
  • ping local address: /n <Count> "Specifies the number of echo Request messages sent. The default is 4."[3][4]

Approach 2: sleep package of CygWin[edit]

Requirement: Install Cygwin on Win Os windows.png & install sleep package (How-to: Setting Up Cygwin/X)

Verify the installation of sleep package[5][6]

  1. Key-in cmd to open command prompt (How to Open Command Prompt (Windows 10, 8, 7, Vista, XP))
  2. Key-in one of following commands
    • Key-in where sleep if you add installation path of CygWin to system path (How to setup my system path). Or
    • Key-in dir C:\cygwin64\bin\sleep.exe if the installation path of CygWin is C:\cygwin64\.
C:\Users\user>dir C:\cygwin64\bin\sleep.exe

# successful condition
C:\cygwin64\bin\sleep.exe

# failed condition
File Not Found

BAT file:

REM print current date & time
ECHO %date% %time%

REM sleep 5 ~ 60 seconds
SET /a timeout=%RANDOM% * 55 / 32767 + 5
C:\cygwin64\bin\sleep.exe %timeout%

REM print current date & time
ECHO %date% %time%

Approach 3: TIMEOUT[edit]

Alternative command: Icon_exclaim.gif The following command ECHO %date% %time% will not be executed after TIMEOUT %timeout% was executed.

BAT file:

SET /a timeout=%RANDOM% * 55 / 32767 + 5
TIMEOUT %timeout%

ECHO %date% %time%

BASH[edit]

Approach1: sleep[edit]

Tested on Linux Os linux.png & Mac icon_os_mac.png [7][8]

# print current date & time
echo $(date '+%Y-%m-%d %H:%M:%S')

# sleep 5 ~ 65 seconds
timeout=$(($RANDOM * 60 / 32768 + 5))
sleep $timeout

# print current date & time
echo $(date '+%Y-%m-%d %H:%M:%S')

Sleep couple microseconds[9]. Tested on Linux Os linux.png

# print current unix timestamp e.g. 1598346362244
date +%s%N

# sleep 1 millisecond = 0.001 seconds
sleep 0.001s

# print current unix timestamp
date +%s%N


Sleep couple microseconds. Tested on Mac icon_os_mac.png

# print current unix timestamp e.g. 1598346362244
php -r 'echo microtime(TRUE) . PHP_EOL;'

# sleep 1 millisecond = 0.001 seconds
sleep 0.001s

# print current unix timestamp
php -r 'echo microtime(TRUE) . PHP_EOL;'


Sleep couple microseconds. Tested on Mac icon_os_mac.png

# print current unix timestamp e.g. 1598346362244
Sleep couple microseconds. Tested on {{Mac}}

<pre>
# print current unix timestamp e.g. 1598346362244
php -r 'echo microtime(TRUE) . PHP_EOL;'

# sleep 1 millisecond = 0.001 seconds
sleep 0.001s

# print current unix timestamp
php -r 'echo microtime(TRUE) . PHP_EOL;'


Sleep couple milliseconds (1 seconds = 1000 milliseconds) e.g. 1671090194.136471987[10]

# print current unix timestamp in milliseconds e.g. 1671090194.136471987
perl -MTime::HiRes=time -e 'printf "%.9f\n", time'

# sleep 1 millisecond = 0.001 seconds
sleep 0.001s

# print current unix timestamp
perl -MTime::HiRes=time -e 'printf "%.9f\n", time'

Approach2: ping[edit]

Tested on Linux Os linux.png & Mac icon_os_mac.png

ping local address: -c <Count> "Stop after sending (and receiving) count ECHO_RESPONSE packets."[11]

# print current date & time
echo $(date '+%Y-%m-%d %H:%M:%S')

# sleep 5 ~ 65 seconds
timeout=$(($RANDOM * 60 / 32768 + 5))
ping 127.0.0.1 -c $timeout > nul

# print current date & time
echo $(date '+%Y-%m-%d %H:%M:%S')

Approach3: usleep[edit]

usleep(3) - Linux man page "suspend execution for microsecond intervals" (1 second = 1 000 000 microsecond). Tested on Linux Os linux.png

# print current date, time & nanoseconds
echo $(date '+%Y-%m-%d %H:%M:%S')$(date '+.%N')

# sleep 0.2 ~ 1.2 seconds
timeout=$(($RANDOM * 1000000 / 32768 + 200000))
echo $timeout
usleep $timeout

# print current date, time & nanoseconds
echo $(date '+%Y-%m-%d %H:%M:%S')$(date '+.%N')

BASH example: download file and sleep random seconds between 1 ~ 7 seconds[edit]

The following script checks if a specific file exists in a defined path. If the file doesn't exist, it downloads the file from a provided URL and then pauses for a random duration between 1 and 7 seconds. If the file already exists, it simply prints a message stating that the file was found and the download was skipped.

if [ ! -f /path/to/paper.pdf ]
then
    curl "https://website/to/pdf" -L -o /path/to/paper.pdf
    sleep $((1 + RANDOM % 7))
else
    echo "File found. Download skipped."
fi

The same command can be written on one line:

if [ ! -f /path/to/paper.pdf ]; then curl "https://website/to/pdf" -L -o /path/to/paper.pdf; sleep $((1 + RANDOM % 7)); else echo "File found. Download skipped."; fi

References

PHP[edit]

JavaScript[edit]

References[edit]

Related[edit]