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2010-03-03 - Commandlinefu @ SXSW 2010
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Commands tagged at

Commands tagged at from sorted by
Terminal - Commands tagged at - 3 results
( trap '' 1; ( nice -n 19 sleep 2h && command rm -v -rf /garbage/ &>/dev/null && trap 1 ) & )
2009-10-10 04:43:44
User: AskApache
Functions: command nice rm sleep trap
Tags: bash trap sleep process nohup logout at askapache nice processes /dev/null HUP SIGHUP
2
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Schedule Nice Background Commands That Won't Die on Logout - Alternative to nohup and at

Check out the usage of 'trap', you may not have seen this one much. This command provides a way to schedule commands at certain times by running them after sleep finishes sleeping. In the example 'sleep 2h' sleeps for 2 hours. What is cool about this command is that it uses the 'trap' builtin bash command to remove the SIGHUP trap that normally exits all processes started by the shell upon logout. The 'trap 1' command then restores the normal SIGHUP behaviour.

It also uses the 'nice -n 19' command which causes the sleep process to be run with minimal CPU.

Further, it runs all the commands within the 2nd parentheses in the background. This is sweet cuz you can fire off as many of these as you want. Very helpful for shell scripts.

Comments (1) | Add to favourites | Report as malicious | Submit alternative | Report as a duplicate
echo init 0 | at now + 2 hours
2009-08-22 08:10:46
User: hemanth
Functions: at echo init
Tags: echo at init
0
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power off system in X hours form the current time, here X=2
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echo "nohup command rm -rf /phpsessions 1>&2 &>/dev/null 1>&2 &>/dev/null&" | at now + 3 hours 1>&2 &>/dev/null
2009-08-18 07:31:17
User: AskApache
Functions: at echo
Tags: cronjob schedule nohup background at
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Schedule a script or command in x num hours, silently run in the background even if logged out

This is helpful for shell scripts, I use it in my custom php install script to schedule to delete the build files in 3 hours, as the php install script is completely automated and is made to run slow.

Does require at, which some environments without crontab still do have.

You can add as many commands to the at you want. Here's how I delete them in case the script gets killed. (trapped)

atq |awk '{print $1}'|xargs -iJ atrm J &>/dev/null

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