Cron tab: crontabs, cron.d, user crontabs, run-parts dirs and systemd timers in one list; next/last run, run now, enable/disable, in-place editing, cron log and output file
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
This commit is contained in:
Mitchell-Johnson
co-authored by
Claude Fable 5.1
Claude Fable 5.1
parent
bc891b1042
commit
41c2f05535
@@ -0,0 +1,163 @@
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package cron
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import (
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"errors"
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"fmt"
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"strconv"
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"strings"
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"time"
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)
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// schedule is a parsed five-field cron expression as sets.
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type schedule struct {
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min, hour, dom, mon, dow [64]bool
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domStar, dowStar bool // "*" in dom/dow changes the match rule
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reboot bool
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}
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var monthNames = map[string]int{"jan": 1, "feb": 2, "mar": 3, "apr": 4, "may": 5, "jun": 6, "jul": 7, "aug": 8, "sep": 9, "oct": 10, "nov": 11, "dec": 12}
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var dayNames = map[string]int{"sun": 0, "mon": 1, "tue": 2, "wed": 3, "thu": 4, "fri": 5, "sat": 6}
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var aliases = map[string]string{
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"@yearly": "0 0 1 1 *", "@annually": "0 0 1 1 *", "@monthly": "0 0 1 * *", "@weekly": "0 0 * * 0",
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"@daily": "0 0 * * *", "@midnight": "0 0 * * *", "@hourly": "0 * * * *",
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}
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func parseSchedule(expr string) (*schedule, error) {
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expr = strings.TrimSpace(expr)
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if expr == "@reboot" {
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return &schedule{reboot: true}, nil
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}
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if a, ok := aliases[strings.ToLower(expr)]; ok {
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expr = a
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}
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f := strings.Fields(expr)
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if len(f) != 5 {
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return nil, errors.New("expected 5 fields")
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}
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s := &schedule{}
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var err error
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if s.min, err = parseField(f[0], 0, 59, nil); err != nil {
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return nil, fmt.Errorf("minute: %w", err)
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}
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if s.hour, err = parseField(f[1], 0, 23, nil); err != nil {
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return nil, fmt.Errorf("hour: %w", err)
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}
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if s.dom, err = parseField(f[2], 1, 31, nil); err != nil {
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return nil, fmt.Errorf("day of month: %w", err)
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}
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if s.mon, err = parseField(f[3], 1, 12, monthNames); err != nil {
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return nil, fmt.Errorf("month: %w", err)
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}
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if s.dow, err = parseField(f[4], 0, 7, dayNames); err != nil {
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return nil, fmt.Errorf("day of week: %w", err)
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}
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if s.dow[7] { // 7 == Sunday
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s.dow[0] = true
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}
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s.domStar = f[2] == "*"
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s.dowStar = f[4] == "*"
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return s, nil
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}
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func parseField(field string, lo, hi int, names map[string]int) ([64]bool, error) {
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var set [64]bool
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atom := func(s string) (int, error) {
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if names != nil {
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if v, ok := names[strings.ToLower(s)]; ok {
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return v, nil
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}
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}
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v, err := strconv.Atoi(s)
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if err != nil {
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return 0, fmt.Errorf("bad value %q", s)
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}
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return v, nil
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}
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for _, part := range strings.Split(field, ",") {
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step := 1
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if i := strings.Index(part, "/"); i >= 0 {
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v, err := strconv.Atoi(part[i+1:])
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if err != nil || v <= 0 {
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return set, fmt.Errorf("bad step in %q", part)
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}
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step, part = v, part[:i]
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}
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a, b := lo, hi
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switch {
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case part == "*":
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case strings.Contains(part, "-"):
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x, y, _ := strings.Cut(part, "-")
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var err error
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if a, err = atom(x); err != nil {
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return set, err
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}
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if b, err = atom(y); err != nil {
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return set, err
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}
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default:
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v, err := atom(part)
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if err != nil {
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return set, err
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}
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a = v
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if step == 1 {
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b = v
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}
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}
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if a < lo || b > hi || a > b {
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return set, fmt.Errorf("out of range: %q", part)
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}
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for v := a; v <= b; v += step {
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set[v] = true
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}
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}
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return set, nil
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}
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func (s *schedule) dayMatches(t time.Time) bool {
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if !s.mon[int(t.Month())] {
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return false
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}
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dom, dow := s.dom[t.Day()], s.dow[int(t.Weekday())]
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switch {
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case s.domStar && s.dowStar:
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return true
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case s.domStar:
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return dow
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case s.dowStar:
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return dom
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default: // both restricted: cron runs when either matches
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return dom || dow
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}
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}
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// nextRun finds the first time strictly after `from` that the schedule fires.
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func nextRun(expr string, from time.Time) (time.Time, bool) {
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s, err := parseSchedule(expr)
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if err != nil || s.reboot {
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return time.Time{}, false
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}
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t := from.Truncate(time.Minute).Add(time.Minute)
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day := time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
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for i := 0; i < 366*2; i++ {
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if s.dayMatches(day) {
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for h := 0; h < 24; h++ {
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if !s.hour[h] {
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continue
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}
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for mi := 0; mi < 60; mi++ {
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if !s.min[mi] {
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continue
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}
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c := time.Date(day.Year(), day.Month(), day.Day(), h, mi, 0, 0, day.Location())
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if !c.Before(t) {
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return c, true
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}
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}
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}
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}
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day = day.AddDate(0, 0, 1)
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}
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return time.Time{}, false
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}
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