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.
આ ડેક વિશે
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.
આ ડેકનાં કાર્ડ
કાર્ડ 1
પ્રશ્ન
GNU find: which stored timestamp does -mtime test?
જવાબ
The last content-modification time (mtime). It does not mean file creation time.
કાર્ડ 2
પ્રશ્ન
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?
જવાબ
fir and elm. Their ages are inside the first 24-hour range; oak has crossed it. Compare membership, not output order.
કાર્ડ 3
પ્રશ્ન
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?
જવાબ
red and blue. -mmin -45 selects timestamps newer than the 45-minute cutoff in this fixture.
કાર્ડ 4
પ્રશ્ન
GNU find: what does the c in -ctime refer to?
જવાબ
Status-change time. Changes to file data or attributes can update ctime; the c does not stand for creation.
કાર્ડ 5
પ્રશ્ન
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?
જવાબ
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.
કાર્ડ 6
પ્રશ્ન
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?
જવાબ
-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.
કાર્ડ 7
પ્રશ્ન
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.
જવાબ
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.
કાર્ડ 8
પ્રશ્ન
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?
જવાબ
copper and zinc. With these off-boundary ages, +0 selects beyond the first 24-hour range. tin is too recent.
કાર્ડ 9
પ્રશ્ન
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'?
જવાબ
No. Newer-than is strict: an identical timestamp fails -newermt.
કાર્ડ 10
પ્રશ્ન
GNU find: complete find ./lab ___ -mtime -1 -print to limit results to regular files.
જવાબ
-type f.
find ./lab -type f -mtime -1 -printThe type test excludes directories; -print lists matching paths.
કાર્ડ 11
પ્રશ્ન
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?
જવાબ
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.
કાર્ડ 12
પ્રશ્ન
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?
જવાબ
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.
કાર્ડ 13
પ્રશ્ન
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?
જવાબ
a and b. Both are under two 24-hour periods in this fixture; c is beyond that range.
કાર્ડ 14
પ્રશ્ન
GNU find: choose -mtime or -ctime to filter by when file contents were last modified.
જવાબ
-mtime. -ctime tracks status changes too, so it is not a substitute when the task specifically asks for content-modification time.
કાર્ડ 15
પ્રશ્ન
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'?
જવાબ
b and c. Both are after 08:00 and no later than 12:00 on October 22. The two adjacent conditions must both succeed.
કાર્ડ 16
પ્રશ્ન
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?
જવાબ
rose only. +45 tests for a timestamp older than the 45-minute cutoff here. It does not wait for a 46-minute age.
કાર્ડ 17
પ્રશ્ન
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.
જવાબ
Use -mtime -2. The minus sign selects the younger range; unsigned 2 selects the two-day range instead.
કાર્ડ 18
પ્રશ્ન
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?
જવાબ
a only. Placing -daystart before -mtime makes this a UTC midnight-based day test. The supplied times avoid midnight endpoints.
કાર્ડ 19
પ્રશ્ન
GNU find: which test takes the literal instant '2026-10-22 12:00:00 UTC': -newer or -newermt?
જવાબ
-newermt. Its t means the reference argument is a parsed time. -newer expects a reference file path.
કાર્ડ 20
પ્રશ્ન
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?
જવાબ
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.
કાર્ડ 21
પ્રશ્ન
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'?
જવાબ
Yes. Equality fails the newer-than test, and ! reverses that result. The negated test includes the bound.
કાર્ડ 22
પ્રશ્ન
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.
જવાબ
Use -mtime +0. +1 omits the 25-hour file; +0 includes both stated older files. All three ages are well away from the cutoff.
કાર્ડ 23
પ્રશ્ન
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?
જવાબ
b and c. They are older than 15 minutes and younger than 40 minutes. Adjacent tests are combined with AND.
કાર્ડ 24
પ્રશ્ન
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?
જવાબ
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.
કાર્ડ 25
પ્રશ્ન
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?
જવાબ
b and c. Both pass the older-than-first-range condition and the younger-than-three-days condition. The result is their intersection.
કાર્ડ 26
પ્રશ્ન
GNU find: can -ctime 0 establish that a file was created within the last day?
જવાબ
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.
કાર્ડ 27
પ્રશ્ન
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'?
જવાબ
No. edge equals the lower bound and fails the first, strict newer-than test. The interval excludes its lower endpoint.
કાર્ડ 28
પ્રશ્ન
GNU find, no -daystart; starts 2026-10-23 18:00 UTC. Regular files have these mtime ages: note 90m. Does it match -mtime 1?
જવાબ
No. Ninety minutes is still in the first 24-hour range. The number 1 in -mtime 1 does not mean one hour.
કાર્ડ 29
પ્રશ્ન
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.
જવાબ
Use -mtime -3. The minus sign selects the younger range. +3 instead selects beyond the three-day range.
કાર્ડ 30
પ્રશ્ન
GNU find: does prefixing a command with TZ=UTC freeze its current time at a particular UTC instant?
જવાબ
No. TZ=UTC chooses the timezone for calendar interpretation. The clock still advances, so an elapsed-age exercise must state its initialization time separately.
કાર્ડ 31
પ્રશ્ન
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'?
જવાબ
Yes. edge is after the lower bound and equal to the upper bound. Negating the upper newer-than test includes that equality.
કાર્ડ 32
પ્રશ્ન
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?
જવાબ
c only. -newer compares each candidate's mtime with the reference file's mtime. Equality fails.
કાર્ડ 33
પ્રશ્ન
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?
જવાબ
old only. +4 goes beyond the four-day range, so the transition is near five days, not four. Both examples avoid the exact cutoff.
કાર્ડ 34
પ્રશ્ન
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?
જવાબ
-mtime -1 only. Ninety minutes exceeds the 60-minute window but is well within the first 24-hour range.
કાર્ડ 35
પ્રશ્ન
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?
જવાબ
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.
કાર્ડ 36
પ્રશ્ન
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'?
જવાબ
c and d. The window is (06:00, 10:00] on October 22: after the lower instant, through the upper instant inclusive.
કાર્ડ 37
પ્રશ્ન
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.
જવાબ
Use -newermt.
find ./lab -type f -newermt '2026-10-22 12:00:00 UTC' -print-newer would interpret the argument as a file path.
કાર્ડ 38
પ્રશ્ન
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?
જવાબ
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.
કાર્ડ 39
પ્રશ્ન
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?
જવાબ
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.
કાર્ડ 40
પ્રશ્ન
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.
જવાબ
Excludes 06:00; includes 10:00. The actual window is (lower, upper], not [lower, upper). Naming calendar boundaries does not reverse the comparisons.
40 કાર્ડ
GNU Find Time Flashcards: -mtime, -mmin & Boundaries
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