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GNU Find Time Flashcards: -mtime, -mmin & Boundaries

Predict GNU find -mtime and -mmin results, repair time filters, and practice -daystart order and explicit timestamp boundaries with small file lists.

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O tomto balíčku

Practice selecting files by time with 40 short GNU find cards. Read a stated clock and file timestamps, predict membership, or repair one condition. All command examples list regular files; output order is irrelevant.

The cards move from timestamp choice and elapsed-day ranges into interleaved minute tests and repairs, then UTC calendar references and explicit timestamp comparisons. They practice command → selected files, task → corrected condition, and selected mistaken claims → repaired explanation. Closely related variants are separated. Exhaustive reverse flag definitions and every equivalent command are excluded: they add ambiguous answers rather than one clear selection decision. Unsigned minute tests are checked against GNU findutils 4.11.0 rather than inferred from day tests.

The scope is GNU find: -mtime, -mmin, a small -amin contrast, -daystart placement, -newermt and -newer. Elapsed examples state the initialization clock and avoid exact age cutoffs. Exact endpoint practice uses explicit timestamps: -newermt LOWER ! -newermt UPPER selects (LOWER, UPPER]. The deck excludes BSD/macOS portability, future timestamps, exact elapsed/daystart cutoff drills, exhaustive date parsing or DST, creation-time filters, deletion, traversal, and shell handoff; those need separate practice.

Original questions, examples, explanations and ordering were authored with AI assistance and checked against the GNU time reference, age-range reference, timestamp-comparison reference and the GNU findutils 4.11.0 release source. The cover is an original AI-generated illustration. CC0 1.0 covers the original deck text, organization, metadata and cover to the extent applicable rights exist; factual behavior is not owned, and GNU documentation and source retain their own licenses. No GNU manual prose, source code or competitor card text is included in the deck.

An independent, unofficial learning resource with no affiliation with or endorsement by GNU or the Free Software Foundation.

Kartičky v tomto balíčku

  1. Kartička 1

    Otázka

    GNU find: which stored timestamp does -mtime test?

    Odpověď

    The last content-modification time (mtime). It does not mean file creation time.

  2. Kartička 2

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: fir 7h20m, elm 23h40m, oak 24h20m. Which match -mtime 0?

    Odpověď

    fir and elm. Their ages are inside the first 24-hour range; oak has crossed it. Compare membership, not output order.

  3. Kartička 3

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: red 12m30s, blue 44m30s, green 45m30s. Which match -mmin -45?

    Odpověď

    red and blue. -mmin -45 selects timestamps newer than the 45-minute cutoff in this fixture.

  4. Kartička 4

    Otázka

    GNU find: what does the c in -ctime refer to?

    Odpověď

    Status-change time. Changes to file data or attributes can update ctime; the c does not stand for creation.

  5. Kartička 5

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: ash 20h, pine 28h, yew 46h, birch 53h. Which match -mtime 1?

    Odpověď

    pine and yew. The unsigned day test selects the one-day range, between 24 and 48 hours here; it does not select every file older than 24 hours.

  6. Kartička 6

    Otázka

    GNU find; regular file note has stored atime 2026-10-23 17:40 UTC and mtime 2026-10-20 17:40 UTC. At 2026-10-23 18:00 UTC, which tests its recent access: -amin -60 or -mmin -60?

    Odpověď

    -amin -60. It tests the supplied access timestamp. -mmin uses the much older modification timestamp. These are stored timestamps, not a claim that every read updates atime.

  7. Kartička 7

    Otázka

    GNU find, no -daystart; regular files all have past mtimes. Change only the time test in find ./lab -type f -mtime -90 -print to select modifications within the last 90 minutes.

    Odpověď

    Use -mmin -90.

    find ./lab -type f -mmin -90 -print

    -mtime measures days; -mmin measures minutes. This is an elapsed window, not a calendar day.

  8. Kartička 8

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: tin 22h, copper 26h, zinc 51h. Which match -mtime +0?

    Odpověď

    copper and zinc. With these off-boundary ages, +0 selects beyond the first 24-hour range. tin is too recent.

  9. Kartička 9

    Otázka

    GNU find; regular files have fixed mtimes in UTC. note is stamped 2026-10-22 09:00:00. Does it match -newermt '2026-10-22 09:00:00 UTC'?

    Odpověď

    No. Newer-than is strict: an identical timestamp fails -newermt.

  10. Kartička 10

    Otázka

    GNU find: complete find ./lab ___ -mtime -1 -print to limit results to regular files.

    Odpověď

    -type f.

    find ./lab -type f -mtime -1 -print

    The type test excludes directories; -print lists matching paths.

  11. Kartička 11

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: dawn 44m30s, noon 45m30s. Which match unsigned -mmin 45 in GNU findutils 4.11.0?

    Odpověď

    dawn only. In 4.11.0, unsigned -mmin 45 selects timestamps within the minute immediately newer than the 45-minute cutoff. Do not copy the unsigned -mtime day-range numbering into minute tests.

  12. Kartička 12

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: clay 46h, slate 49h, chalk 73h. Which match -mtime +1?

    Odpověď

    slate and chalk. +1 goes beyond the one-day range, so 46 hours is too recent. These ages stay away from the exact 48-hour cutoff.

  13. Kartička 13

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: a 17h, b 47h, c 50h. Which match -mtime -2?

    Odpověď

    a and b. Both are under two 24-hour periods in this fixture; c is beyond that range.

  14. Kartička 14

    Otázka

    GNU find: choose -mtime or -ctime to filter by when file contents were last modified.

    Odpověď

    -mtime. -ctime tracks status changes too, so it is not a substitute when the task specifically asks for content-modification time.

  15. Kartička 15

    Otázka

    GNU find; regular files have fixed mtimes in UTC. a is 2026-10-22 07:00, b 09:00, c 11:00, d 13:00. Which match -newermt '2026-10-22 08:00:00 UTC' ! -newermt '2026-10-22 12:00:00 UTC'?

    Odpověď

    b and c. Both are after 08:00 and no later than 12:00 on October 22. The two adjacent conditions must both succeed.

  16. Kartička 16

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: iris 44m30s, rose 45m30s. Which match -mmin +45?

    Odpověď

    rose only. +45 tests for a timestamp older than the 45-minute cutoff here. It does not wait for a 46-minute age.

  17. Kartička 17

    Otázka

    GNU find, no -daystart; regular files have past mtimes, none within a minute of a 24-hour boundary. Change only 2 in -mtime 2 to select every file younger than two days.

    Odpověď

    Use -mtime -2. The minus sign selects the younger range; unsigned 2 selects the two-day range instead.

  18. Kartička 18

    Otázka

    GNU find; regular files have fixed mtimes in UTC. a is 2026-10-22 22:00, b 2026-10-23 02:00, c 2026-10-21 22:00. At 2026-10-23 18:00 UTC, which match TZ=UTC find ./lab -daystart -type f -mtime 1 -print?

    Odpověď

    a only. Placing -daystart before -mtime makes this a UTC midnight-based day test. The supplied times avoid midnight endpoints.

  19. Kartička 19

    Otázka

    GNU find: which test takes the literal instant '2026-10-22 12:00:00 UTC': -newer or -newermt?

    Odpověď

    -newermt. Its t means the reference argument is a parsed time. -newer expects a reference file path.

  20. Kartička 20

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: mint 47h, sage 58h, thyme 71h, basil 74h. Which match -mtime 2?

    Odpověď

    sage and thyme. Their ages fall inside the two-day range, between 48 and 72 hours here. mint is too young; basil is too old.

  21. Kartička 21

    Otázka

    GNU find; regular files have fixed mtimes in UTC. log is stamped 2026-10-22 15:00:00. Does it match ! -newermt '2026-10-22 15:00:00 UTC'?

    Odpověď

    Yes. Equality fails the newer-than test, and ! reverses that result. The negated test includes the bound.

  22. Kartička 22

    Otázka

    GNU find, no -daystart; regular files are aged 23h, 25h and 49h at 2026-10-23 18:00 UTC. Change only +1 in -mtime +1 to select the 25h and 49h files.

    Odpověď

    Use -mtime +0. +1 omits the 25-hour file; +0 includes both stated older files. All three ages are well away from the cutoff.

  23. Kartička 23

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: a 14m30s, b 16m30s, c 39m30s, d 40m30s. Which match -mmin +15 -mmin -40?

    Odpověď

    b and c. They are older than 15 minutes and younger than 40 minutes. Adjacent tests are combined with AND.

  24. Kartička 24

    Otázka

    GNU find; regular files have fixed mtimes in UTC. a is 2026-10-22 22:00, b 2026-10-22 10:00. At 2026-10-23 18:00 UTC, which match TZ=UTC find ./lab -type f -mtime 1 -daystart -print?

    Odpověď

    b only. -daystart comes too late to affect the earlier -mtime test. The ages are 20 hours and 32 hours; only b is in the elapsed one-day range.

  25. Kartička 25

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: a 12h, b 30h, c 60h, d 80h. Which match -mtime +0 -mtime -3?

    Odpověď

    b and c. Both pass the older-than-first-range condition and the younger-than-three-days condition. The result is their intersection.

  26. Kartička 26

    Otázka

    GNU find: can -ctime 0 establish that a file was created within the last day?

    Odpověď

    No. It tests recent status change, which can happen to an old file. Creation or birth time is a separate timestamp and is outside this deck's filters.

  27. Kartička 27

    Otázka

    GNU find; regular files have fixed mtimes in UTC. edge is stamped 2026-10-22 06:00:00. Is it selected by -newermt '2026-10-22 06:00:00 UTC' ! -newermt '2026-10-22 10:00:00 UTC'?

    Odpověď

    No. edge equals the lower bound and fails the first, strict newer-than test. The interval excludes its lower endpoint.

  28. Kartička 28

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: note 90m. Does it match -mtime 1?

    Odpověď

    No. Ninety minutes is still in the first 24-hour range. The number 1 in -mtime 1 does not mean one hour.

  29. Kartička 29

    Otázka

    GNU find, no -daystart; regular files have past mtimes, none near a 24-hour boundary. Change only +3 in -mtime +3 to select files younger than three days.

    Odpověď

    Use -mtime -3. The minus sign selects the younger range. +3 instead selects beyond the three-day range.

  30. Kartička 30

    Otázka

    GNU find: does prefixing a command with TZ=UTC freeze its current time at a particular UTC instant?

    Odpověď

    No. TZ=UTC chooses the timezone for calendar interpretation. The clock still advances, so an elapsed-age exercise must state its initialization time separately.

  31. Kartička 31

    Otázka

    GNU find; regular files have fixed mtimes in UTC. edge is stamped 2026-10-22 10:00:00. Is it selected by -newermt '2026-10-22 06:00:00 UTC' ! -newermt '2026-10-22 10:00:00 UTC'?

    Odpověď

    Yes. edge is after the lower bound and equal to the upper bound. Negating the upper newer-than test includes that equality.

  32. Kartička 32

    Otázka

    GNU find; regular reference file ./ref has mtime 2026-10-22 12:00:00 UTC and lies outside ./lab. Regular files in ./lab have mtimes a 11:59:00, b 12:00:00, c 12:01:00 that day. Which match -newer ./ref?

    Odpověď

    c only. -newer compares each candidate's mtime with the reference file's mtime. Equality fails.

  33. Kartička 33

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: old 5d20m, recent 4d20m. Which match -mtime +4?

    Odpověď

    old only. +4 goes beyond the four-day range, so the transition is near five days, not four. Both examples avoid the exact cutoff.

  34. Kartička 34

    Otázka

    GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: report 90m. Which selects it: -mmin -60 or -mtime -1?

    Odpověď

    -mtime -1 only. Ninety minutes exceeds the 60-minute window but is well within the first 24-hour range.

  35. Kartička 35

    Otázka

    GNU find; regular files have fixed mtimes in UTC. a is 2026-10-22 23:00, b 2026-10-23 03:00, c 2026-10-23 17:00. At 2026-10-23 18:00 UTC, which match TZ=UTC find ./lab -daystart -type f -mtime 0 -print?

    Odpověď

    b and c. With -daystart before the test, these past timestamps fall in the current UTC day range. a is in the previous day. No fixture file is stamped at midnight.

  36. Kartička 36

    Otázka

    GNU find; regular files have fixed mtimes in UTC. a is 2026-10-22 05:59:59, b 06:00:00, c 08:00:00, d 10:00:00, e 10:00:01. Which match -newermt '2026-10-22 06:00:00 UTC' ! -newermt '2026-10-22 10:00:00 UTC'?

    Odpověď

    c and d. The window is (06:00, 10:00] on October 22: after the lower instant, through the upper instant inclusive.

  37. Kartička 37

    Otázka

    GNU find; regular files have fixed mtimes. Change only the test name in find ./lab -type f -newer '2026-10-22 12:00:00 UTC' -print to compare against that literal instant.

    Odpověď

    Use -newermt.

    find ./lab -type f -newermt '2026-10-22 12:00:00 UTC' -print

    -newer would interpret the argument as a file path.

  38. Kartička 38

    Otázka

    GNU find, no -daystart; regular files have past mtimes, each at least a minute from a 24-hour boundary. Do -mtime 0 and -mtime -1 select the same set?

    Odpověď

    Yes, under these assumptions. Both select the supplied files inside the first 24-hour range. This is not a rule for future timestamps or exact cutoff instants.

  39. Kartička 39

    Otázka

    GNU find, TZ=UTC; regular file journal has mtime 2026-10-22 23:00 UTC. At 2026-10-23 18:00 UTC, does plain -mtime 1 select this file from yesterday?

    Odpověď

    No. It is only 19 hours old. Yesterday's calendar date and the elapsed one-day range are different targets. -daystart before the test changes the reference.

  40. Kartička 40

    Otázka

    GNU find uses -newermt '2026-10-22 06:00:00 UTC' ! -newermt '2026-10-22 10:00:00 UTC' on regular files. Repair the claim “includes 06:00, excludes 10:00” for those UTC instants.

    Odpověď

    Excludes 06:00; includes 10:00. The actual window is (lower, upper], not [lower, upper). Naming calendar boundaries does not reverse the comparisons.

Three file folders beside a blank clock-like disc, with a teal window highlighting two folders.

40 kartiček

GNU Find Time Flashcards: -mtime, -mmin & Boundaries

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