Delete all files except the newest 3 in bash script

Question

Question: How do you delete all files in a directory except the newest 3?

Finding the newest 3 files is simple:

ls -t | head -3
         


        

Answer 1

Recursive script with arbitrary num of files to keep per-directory

Also handles files/dirs with spaces, newlines and other odd characters

#!/bin/bash
if (( $# != 2 )); then
  echo "Usage: $0  "
  exit
fi

while IFS= read -r -d $'\0' dir; do
  # Find the nth oldest file
  nthOldest=$(find "$dir" -maxdepth 1 -type f -printf '%T@\0%p\n' | sort -t '\0' -rg \
    | awk -F '\0' -v num="$2" 'NR==num+1{print $2}')

  if [[ -f "$nthOldest" ]]; then
    find "$dir" -maxdepth 1 -type f ! -newer "$nthOldest" -exec rm {} +
  fi
done < <(find "$1" -type d -print0)

Proof of concept

$ tree test/
test/
├── sub1
│   ├── sub1_0_days_old.txt
│   ├── sub1_1_days_old.txt
│   ├── sub1_2_days_old.txt
│   ├── sub1_3_days_old.txt
│   └── sub1\ 4\ days\ old\ with\ spaces.txt
├── sub2\ with\ spaces
│   ├── sub2_0_days_old.txt
│   ├── sub2_1_days_old.txt
│   ├── sub2_2_days_old.txt
│   └── sub2\ 3\ days\ old\ with\ spaces.txt
└── tld_0_days_old.txt

2 directories, 10 files
$ ./keepNewest.sh test/ 2
$ tree test/
test/
├── sub1
│   ├── sub1_0_days_old.txt
│   └── sub1_1_days_old.txt
├── sub2\ with\ spaces
│   ├── sub2_0_days_old.txt
│   └── sub2_1_days_old.txt
└── tld_0_days_old.txt

2 directories, 5 files