mirror of
https://github.com/notwa/rc
synced 2024-11-05 02:59:03 -08:00
63 lines
2.1 KiB
Bash
Executable file
63 lines
2.1 KiB
Bash
Executable file
#!/usr/bin/env dash
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# compat: +ash +bash +dash -hush -ksh +mksh +oksh +osh +posh +yash +zsh
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minutemaid() { ### @-
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### check if the current minute is divisible by a given number,
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### and optionally execute a command if it is. if a command is given,
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### either execute the command and return its exit value,
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### or execute nothing and return 0. if a command is omitted,
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### either return 0 on the minute, or return 1.
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###
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### note that a "minute" is relative to the seconds since the epoch,
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### not the minute of the hour. this ensures that commands will run
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### roughly every N minutes, regardless of the minute hand on the clock.
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###
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### note that `minutemaid 1` will always return 0,
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### and `minutemaid 1 command` will always execute the command,
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### since every integral interval is evenly divisible by 1.
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### `minutemaid 0`, and any negative interval, is an error.
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###
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### ```
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### # crontab usage:
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### * * * * * minutemaid 9 ~/work/do_my_bidding # runs every nine minutes
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### # loop usage:
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### until minutemaid 9; do sleep 5; done
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### echo the wait is finally over; date
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### # improper usage:
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### while minutemaid 1; do sleep 1; done
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### echo this will never happen
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### ```
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local offset=0 name=
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while getopts 'o:h' name; do
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case $name in
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o) offset="$OPTARG";;
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?) local fd=0 # FIXME: this also matches single-character filenames!
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[ $name = h ] && fd=1 || fd=2
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printf '%s\n' "usage: $0 [-o offset] {interval} [{command} [{args...}]]" >&$fd
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[ $name = h ] && return 0 || return 1;;
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esac
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done
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shift $((OPTIND-1))
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local interval="${1:?no interval specified}"
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shift
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if [ "$interval" -gt 0 ] 2>/dev/null; then
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:
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else
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printf "%s\n" "$0: interval must be a positive integer" >&2
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return 1
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fi
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local sec="$(date +%s)"
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local min="$((sec/60+offset))"
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local mod="$((min%interval))"
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if [ $# -gt 0 ]; then
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[ $mod -ne 0 ] || "$@"
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else
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[ $mod -eq 0 ] && return 0 || return 1
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fi
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}
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[ -n "${preload+-}" ] || minutemaid "$@"
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