Delete All Files Except the Newest 3 in Bash Script

Delete all files except the newest 3 in bash script

This will list all files except the newest three:

ls -t | tail -n +4

This will delete those files:

ls -t | tail -n +4 | xargs rm --

This will also list dotfiles:

ls -At | tail -n +4

and delete with dotfiles:

ls -At | tail -n +4 | xargs rm --

But beware: parsing ls can be dangerous when the filenames contain funny characters like newlines or spaces. If you are certain that your filenames do not contain funny characters then parsing ls is quite safe, even more so if it is a one time only script.

If you are developing a script for repeated use then you should most certainly not parse the output of ls and use the methods described here: http://mywiki.wooledge.org/ParsingLs

How to delete all files except the N newest files?

You can use this command,

ssh -t xxx.xxx.xxx.xxx "cd /directory_wanted; ls -t *.tgz  | tail -n
+11 | xargs rm -f; bash"

In side quotes, we can add what ever the operations to be performed in remote machine. But every command should be terminated with semicolon (;)

Note: Included the same command suggested by silentMonk. It is simple and it is working. But verify it once before performing the operation.

how to delete all files except the latest three in a folder

Alright, there are a few things wrong with your script.

First, and most problematically, is this line:

ls -t /var/path/to/folder |head -n 3;

ls -t will return a list of files in order of their last modification time, starting with the most recently modified. head -n 3 says to only list the first three lines. So what this is saying is "give me a list of only the three most recently modified files", which I don't think is what you want.

I'm not really sure what you're doing with the second ls command, but I'm pretty sure that's just going to concatenate all the files in the directory into your list. That means when it gets sorted and uniq'ed, you'll just be left with an alphabetical list of all the files in that directory. When this gets passed to something like xargs rm, you'll wipe out everything in that directory.

Next, sort | uniq doesn't need the uniq part. You can just use the -u switch on sort to get rid of duplicates. You don't need this part anyway.

Finally, the actual removal of the directory. On that part, you had it right in your question: just use rm -r

Here's the easiest way I can think to do this:

ls -t1 /var/path/to/folder | tail -n +4 | xargs rm -r

Here's what's happening here:

ls -t1 is printing a list, one file/directory per line, of all files in /var/path/to/folder, ordering by the most recent modification date.
tail -n +4 is printing all lines in the output of ls -t1 starting with the fourth line (i.e. the three most recently modified files won't be listed)
xargs rm -r says to delete any file output from the tail. The -r means to recursively delete files, so if it encounters a directory, it will delete everything in that directory, then delete the directory itself.

Note that I'm not sorting anything or removing any duplicates. That's because:

ls only reports a file once, so there are no duplicates to remove
You're deleting every file passed anyway, so it doesn't matter in what order they're deleted.

Does all of that make sense?

Edit:

Since I was wrong about ls specifying the full path when passed an absolute directory, and since you might not be able to perform a cd, perhaps you could use tail instead.

For example:

 ls -t1 /var/path/to/folder | tail -n +4 | xargs find /var/path/to/folder -name $1 | xargs rm -r

Delete all but the most recent X files in bash

For Linux (GNU tools), an efficient & robust way to keep the n newest files in the current directory while removing the rest:

n=5

find . -maxdepth 1 -type f -printf '%T@ %p\0' |
sort -z -nrt ' ' -k1,1 |
sed -z -e "1,${n}d" -e 's/[^ ]* //' |
xargs -0r rm -f

For BSD, find doesn't have the -printf predicate, stat can't output NULL bytes, and sed + awk can't handle NULL-delimited records.

Here's a solution that doesn't support newlines in paths but that safeguards against them by filtering them out:

#!/bin/bash
n=5

find . -maxdepth 1 -type f ! -path $'*\n*' -exec stat -f '%.9Fm %N' {} + |
sort -nrt ' ' -k1,1 |
awk -v n="$n" -F'^[^ ]* ' 'NR > n {printf "%s%c", $2, 0}' |
xargs -0 rm -f

^{note: I'm using bash because of the $'\n' notation. For sh you can define a variable containing a literal newline and use it instead.}

Solution for UNIX & Linux (inspired from AIX/HP-UX/SunOS/BSD/Linux ls -b):

Some platforms don't provide find -printf, nor stat, nor support NULL-delimited records with stat/sort/awk/sed/xargs. That's why using perl is probably the most portable way to tackle the problem, because it is available by default in almost every OS.

I could have written the whole thing in perl but I didn't. I only use it for substituting stat and for encoding-decoding-escaping the filenames. The core logic is the same than the other solutions above and is implemented with POSIX tools.

BTW, perl's default stat has a resolution of a second, but starting from perl-5.8.9 you can get sub-second resolution with the the stat function of the module Time::HiRes (when the OS and the filesystem support it). That's what I'm using here; if your perl doesn't provide it then you can remove the ‑MTime::HiRes=stat from the command line.

n=5

find . '(' -name '.' -o -prune ')' -type f \
-exec perl -MTime::HiRes=stat -l -e '
    foreach (@ARGV) {
        @st = stat($_);
        if ( @st > 0 ) {
            s/([\\\n])/sprintf( "\\%03o", ord($1) )/ge;
            print sprintf( "%.9f %s", $st[9], $_ );
        }
        else { print STDERR "stat: $_: $!"; }
    }
' {} + |

sort -nrt ' ' -k1,1 |

sed -e "1,${n}d" -e 's/[^ ]* //' |

perl -l -ne '
    s/\\([0-7]{3})/chr(oct($1))/ge;
    s/(["\n])/"\\$1"/g;
    print "\"$_\""; 
' |

xargs -E '' sh -c '[ "$#" -gt 0 ] && rm -f "$@"' sh

Explanations:

For each file found, the first perl gets the modification time and outputs it along the encoded filename (each newline and backslash characters are replaced with the literals \n and \\ respectively).
Now each time filename is guaranteed to be single-line, so POSIX sort and sed can safely work with this stream.
The second perl decodes the filenames and escapes them for POSIX xargs.
Lastly, xargs calls rm for deleting the files. The sh command is a trick that prevents xargs from running rm when there's no files to delete.

Delete all folders execpt the last 10 versions

To preserve 10 directories (or fewer) and assuming GNU tools are available, you could us this null-terminated pipeline if there are no other files in this directory:

printf '%s\0' * | sort -zVr | tail -zn+11 | xargs -r0 rm -r --

Delete All Files Except the Newest 3 in Bash Script