Delete all but the most recent X files in bash
The problems with the existing answers:
- inability to handle filenames with embedded spaces or newlines.
- in the case of solutions that invoke
rm
directly on an unquoted command substitution (rm `...`
), there's an added risk of unintended globbing.
- in the case of solutions that invoke
- inability to distinguish between files and directories (i.e., if directories happened to be among the 5 most recently modified filesystem items, you'd effectively retain fewer than 5 files, and applying
rm
to directories will fail).
wnoise's answer addresses these issues, but the solution is GNU-specific (and quite complex).
Here's a pragmatic, POSIX-compliant solution that comes with only one caveat: it cannot handle filenames with embedded newlines - but I don't consider that a real-world concern for most people.
For the record, here's the explanation for why it's generally not a good idea to parse ls
output: http://mywiki.wooledge.org/ParsingLs
ls -tp | grep -v '/$' | tail -n +6 | xargs -I {} rm -- {}
Note: This command operates in the current directory; to target a directory explicitly, use a subshell ((...)
) with cd
:(cd /path/to && ls -tp | grep -v '/$' | tail -n +6 | xargs -I {} rm -- {})
The same applies analogously to the commands below.
The above is inefficient, because xargs
has to invoke rm
separately for each filename.
However, your platform's specific xargs
implementation may allow you to solve this problem:
A solution that works with GNU xargs
is to use -d '\n'
, which makes xargs
consider each input line a separate argument, yet passes as many arguments as will fit on a command line at once:
ls -tp | grep -v '/$' | tail -n +6 | xargs -d '\n' -r rm --
Note: Option -r
(--no-run-if-empty
) ensures that rm
is not invoked if there's no input.
A solution that works with both GNU xargs
and BSD xargs
(including on macOS) - though technically still not POSIX-compliant - is to use -0
to handle NUL
-separated input, after first translating newlines to NUL
(0x0
) chars., which also passes (typically) all filenames at once:
ls -tp | grep -v '/$' | tail -n +6 | tr '\n' '\0' | xargs -0 rm --
Explanation:
ls -tp
prints the names of filesystem items sorted by how recently they were modified , in descending order (most recently modified items first) (-t
), with directories printed with a trailing/
to mark them as such (-p
).- Note: It is the fact that
ls -tp
always outputs file / directory names only, not full paths, that necessitates the subshell approach mentioned above for targeting a directory other than the current one ((cd /path/to && ls -tp ...)
).
- Note: It is the fact that
grep -v '/$'
then weeds out directories from the resulting listing, by omitting (-v
) lines that have a trailing/
(/$
).- Caveat: Since a symlink that points to a directory is technically not itself a directory, such symlinks will not be excluded.
tail -n +6
skips the first 5 entries in the listing, in effect returning all but the 5 most recently modified files, if any.
Note that in order to excludeN
files,N+1
must be passed totail -n +
.xargs -I {} rm -- {}
(and its variations) then invokes onrm
on all these files; if there are no matches at all,xargs
won't do anything.xargs -I {} rm -- {}
defines placeholder{}
that represents each input line as a whole, sorm
is then invoked once for each input line, but with filenames with embedded spaces handled correctly.--
in all cases ensures that any filenames that happen to start with-
aren't mistaken for options byrm
.
A variation on the original problem, in case the matching files need to be processed individually or collected in a shell array:
# One by one, in a shell loop (POSIX-compliant):
ls -tp | grep -v '/$' | tail -n +6 | while IFS= read -r f; do echo "$f"; done
# One by one, but using a Bash process substitution (<(...),
# so that the variables inside the `while` loop remain in scope:
while IFS= read -r f; do echo "$f"; done < <(ls -tp | grep -v '/$' | tail -n +6)
# Collecting the matches in a Bash *array*:
IFS=$'\n' read -d '' -ra files < <(ls -tp | grep -v '/$' | tail -n +6)
printf '%s\n' "${files[@]}" # print array elements
Remove all but 5 (or whatever number) of the most recent files in a directory.
rm `ls -t | awk 'NR>5'`