Linux – How to recursively find and list the latest modified files in a directory with subdirectories and times

filesystemslinuxrecursiontime

Operating system: Linux
Filesystem type: ext3
Preferred solution: Bash (script/one-liner), Ruby, or Python

I have several directories with several subdirectories and files in them. I need to make a list of all these directories that is constructed in a way such that every first-level directory is listed next to the date and time of the latest created/modified file within it.

To clarify, if I touch a file or modify its contents a few subdirectory levels down, that timestamp should be displayed next to the first-level directory name. Say I have a directory structured like this:

./alfa/beta/gamma/example.txt

and I modify the contents of the file example.txt, I need that time displayed next to the first-level directory alfa in human readable form, not epoch. I've tried some things using find, xargs, sort and the like, but I can't get around the problem that the filesystem timestamp of 'alfa' doesn't change when I create/modify files a few levels down.

Best Answer

Try this one:

#!/bin/bash
find $1 -type f -exec stat --format '%Y :%y %n' "{}" \; | sort -nr | cut -d: -f2- | head

Execute it with the path to the directory where it should start scanning recursively (it supports filenames with spaces).

If there are lots of files it may take a while before it returns anything. Performance can be improved if we use xargs instead:

#!/bin/bash
find $1 -type f -print0 | xargs -0 stat --format '%Y :%y %n' | sort -nr | cut -d: -f2- | head

which is a bit faster.

FAT32:

Maximum number of files: 268,173,300
Maximum number of files per directory: 2¹⁶ - 1 (65,535)
Maximum file size: 2 GiB - 1 without LFS, 4 GiB - 1 with

NTFS:

Maximum number of files: 2³² - 1 (4,294,967,295)
Maximum file size
- Implementation: 2⁴⁴ - 2⁶ bytes (16 TiB - 64 KiB)
- Theoretical: 2⁶⁴ - 2⁶ bytes (16 EiB - 64 KiB)
Maximum volume size
- Implementation: 2³² - 1 clusters (256 TiB - 64 KiB)
- Theoretical: 2⁶⁴ - 1 clusters (1 YiB - 64 KiB)

ext2:

Maximum number of files: 10¹⁸
Maximum number of files per directory: ~1.3 × 10²⁰ (performance issues past 10,000)
Maximum file size
- 16 GiB (block size of 1 KiB)
- 256 GiB (block size of 2 KiB)
- 2 TiB (block size of 4 KiB)
- 2 TiB (block size of 8 KiB)
Maximum volume size
- 4 TiB (block size of 1 KiB)
- 8 TiB (block size of 2 KiB)
- 16 TiB (block size of 4 KiB)
- 32 TiB (block size of 8 KiB)

ext3:

Maximum number of files: min(volumeSize / 2¹³, numberOfBlocks)
Maximum file size: same as ext2
Maximum volume size: same as ext2

ext4:

Maximum number of files: 2³² - 1 (4,294,967,295)
Maximum number of files per directory: unlimited
Maximum file size: 2⁴⁴ - 1 bytes (16 TiB - 1)
Maximum volume size: 2⁴⁸ - 1 bytes (256 TiB - 1)

Linux – What characters are forbidden in Windows and Linux directory names

Let's keep it simple and answer the question, first.

The forbidden printable ASCII characters are:

Linux/Unix:
```
  / (forward slash)
```

Windows:

  < (less than)
  > (greater than)
  : (colon - sometimes works, but is actually NTFS Alternate Data Streams)
  " (double quote)
  / (forward slash)
  \ (backslash)
  | (vertical bar or pipe)
  ? (question mark)
  * (asterisk)

Non-printable characters

If your data comes from a source that would permit non-printable characters then there is more to check for.
- Linux/Unix:
```
  0 (NULL byte)
```
- Windows:
```
  0-31 (ASCII control characters)
```
^{Note: While it is legal under Linux/Unix file systems to create files with control characters in the filename, it might be a nightmare for the users to deal with such files.}

Reserved file names

The following filenames are reserved:

Windows:

  CON, PRN, AUX, NUL 
  COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9
  LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, LPT9

(both on their own and with arbitrary file extensions, e.g. LPT1.txt).

Other rules
- Windows:
  
  Filenames cannot end in a space or dot.
- macOS:
  
  You didn't ask for it, but just in case: Colon : and forward slash / depending on context are not permitted (e.g. Finder supports slashes, terminal supports colons). For details see https://superuser.com/questions/326103/what-are-invalid-characters-for-a-file-name-under-os-x