compare file's date bash

Question

I'm working on a tiny dropbox-like bash script, how can I compare the dates of 2 files and replace the old one(s) with the new one without using rsync is there any simple way to process this? can the SHA1 help me with knowing the newer?

It really depends on what you mean by the "date of a file". You are probably referring to `mtime`, but specificity is good. — William Pursell, Feb 10 '13 at 21:32
For the record, the SHA1 absolutely does not reveal anything about the file's age, or name, or contents. — tripleee, Sep 22 '21 at 04:22

score 128 · Accepted Answer · answered Feb 10 '13 at 21:35

128

You can compare file modification times with test, using -nt (newer than) and -ot (older than) operators:

if [ "$file1" -ot "$file2" ]; then
    cp -f "$file2" "$file1"
fi

answered Feb 10 '13 at 21:35

Anton Kovalenko

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that's awesome :))) never thought the simple compare could do the job since i'm new to centOS :) thank u :) – Wael hamadeh Feb 10 '13 at 21:41
-nt seems to mean newer than or same age. – Joe C Jan 06 '15 at 16:23
@JoeC I tested and if same age returned 1 (after `touch -r ...`) – Aquarius Power Feb 06 '15 at 18:31
"$file1" not present implies true / cp ... ? – Sam Ginrich Jan 15 '22 at 16:41
If the files are the same, -ot and -nt return false (1). An absent file is treated as older than a present file. – mwfearnley Mar 18 '22 at 13:10

score 9 · Answer 2 · answered Jan 29 '17 at 20:16

9

Here is a POSIX solution:

find -name file2 -newer file1

answered Jan 29 '17 at 20:16

Zombo

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score 6 · Answer 3 · answered Apr 22 '16 at 13:35

6

Or even shorter and nicer, look at man stat:

stat -c %y file

answered Apr 22 '16 at 13:35

whatever4711

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Use %Y for seconds since epoch, much easier to use. – bugmenot123 Apr 20 '19 at 22:01
This is not portable, though. POSIX `stat` has a rather depressingly narrow set of options. – tripleee Aug 29 '19 at 06:21
1

For anyone else running into this problem: If `FILE` is a symlink to another file, then `stat -c %Y FILE` will output the last-modified-date of the *symlink*, not the file the link is pointing at. Use `stat -L -c %Y FILE` in this case. – balu Oct 09 '19 at 23:45

score 2 · Answer 4 · answered Feb 10 '13 at 21:35

2

how about

 stat file|awk -F': ' '/Modify: /{print $2}'

answered Feb 10 '13 at 21:35

Kent

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This one helped me out with what I was trying to accomplish. Now, how to compare those times? I'm using the answers found here: http://stackoverflow.com/questions/8116503/how-to-compare-two-datetime-strings-and-return-difference-in-hours-bash-shell Perfect! – harperville Dec 31 '13 at 16:11

compare file's date bash

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