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Q&A Recursively remove files with the same name as the ones that end in `.part`

It is incorrect for two reasons. 1. File names containing glob characters This is an edge case scenario. Consider this structure: . ├── abc ├── abc.part ├── cde └── c*e.part The outermos...

posted 1y ago by Quasímodo‭  ·  edited 1y ago by Quasímodo‭

Answer
#2: Post edited by user avatar Quasímodo‭ · 2023-02-11T15:37:29Z (about 1 year ago)
Recursive
  • It is incorrect for several reasons.
  • ### You did not restrict Find's depth
  • It will thus descend into subdirectories and delete matching files there too.
  • Easily solvable by adding `-maxdepth 1` to each Find.
  • ### File names containing [glob characters](https://www.gnu.org/software/bash/manual/html_node/Filename-Expansion.html)
  • This is an edge case scenario.
  • Consider this structure:
  • ```
  • .
  • ├── abc
  • ├── abc.part
  • ├── cde
  • └── c*e.part
  • ```
  • The outermost Find will find
  • - `abc.part`, so `base=abc` and the innermost Find looks for files matching the glob `abc*`, which matches the `abc` file. Good.
  • - `c*e.part`, so `base=c*e` and the innermost Find looks for files matching the glob `c*e*`, which matches the `cde` file. Bad, because `cde` does not contain `c*e`.
  • ### File names with extra characters
  • If you have `abcde` and `abc.part` files, the former will be deleted because it matches `abc*` as should be clear from the previous case discussion.
  • This particular problem would be easily fixed by changing `$base*` -> `$base.*`.
  • ## Solutions
  • You only want to operate in the current directory, so why not
  • for f in *.part; do
  • rm "${f%.part}."*
  • done
  • Here it is crucial **not** to quote the `*`, because we want it to act as a glob (and not literally).
  • `${f%suffix}` is a special form of [parameter expansion](https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html) available in all POSIX shells. It means "remove `suffix` from the expansion of `f`". It looks cleaner than Basename and doesn't spawn an extra process.
  • For something more along the lines you suggested,
  • find . -maxdepth 1 -name '*.part' -exec sh -c 'rm "$(basename "$1" .part)".*' sh {} \;
  • But it looks considerably convoluted and `-maxdepth 1` is not a [POSIX specified option to Find](https://pubs.opengroup.org/onlinepubs/9699919799/utilities/find.html), so you are also sacrificing portability. (It is possible to write the POSIX equivalent of `-maxdepth 1` but it adds obscurity.)
  • It is incorrect for two reasons.
  • ### 1. File names containing [glob characters](https://www.gnu.org/software/bash/manual/html_node/Filename-Expansion.html)
  • This is an edge case scenario.
  • Consider this structure:
  • ```
  • .
  • ├── abc
  • ├── abc.part
  • ├── cde
  • └── c*e.part
  • ```
  • The outermost Find will find
  • - `abc.part`, so `base=abc` and the innermost Find looks for files matching the glob `abc*`, which matches the `abc` file. Good.
  • - `c*e.part`, so `base=c*e` and the innermost Find looks for files matching the glob `c*e*`, which matches the `cde` file. Bad, because `cde` does not contain `c*e`.
  • ### 2. File names with extra characters
  • If you have `abcde` and `abc.part` files, the former will be deleted because it matches `abc*` as should be clear from the previous case discussion.
  • This particular problem would be easily fixed by changing `$base*` -> `$base.*`.
  • ## Proposed solution
  • Point 1 is the real challenge: It is quite involved to feed the file names back again into another Find's `-name` argument _and_ escape the meta-characters, which is always a mine field.
  • I propose instead to use a shell with support for `**`, the recursive glob, for example Bash or Ksh with `globstar` option set or Zsh.
  • #!/bin/bash
  • shopt -s globstar #Not needed in Zsh
  • for f in ./**/*.part; do
  • rm ./**/"$(basename "$f" .part)".*
  • done
  • For a breakdown,
  • - In line 2, **`**/*.part`** matches `./a.part` but also `./a/b/c.part` (hence "recursive glob").
  • - In line 3, **`"$(basename "$f" .part)"`** removes all directory components of the file name and its `.part` extension. This would boil down to `a` and `c` in our example.
  • So the full line **`rm ./**/"$(basename "$f" .part)".*`** recursively removes files matching the `a.*` and `c.*` patterns.
  • It is crucial **not** to quote the `*` characters in the example, because we want it to act as a glob (and not to be parsed literally).
#1: Initial revision by user avatar Quasímodo‭ · 2023-01-13T21:19:19Z (about 1 year ago)
It is incorrect for several reasons.

### You did not restrict Find's depth

It will thus descend into subdirectories and delete matching files there too.

Easily solvable by adding `-maxdepth 1` to each Find.

### File names containing [glob characters](https://www.gnu.org/software/bash/manual/html_node/Filename-Expansion.html)

This is an edge case scenario.

Consider this structure:

```
.
├── abc
├── abc.part
├── cde
└── c*e.part
```

The outermost Find will find

- `abc.part`, so `base=abc` and the innermost Find looks for files matching the glob `abc*`, which matches the `abc` file. Good.
- `c*e.part`, so `base=c*e` and the innermost Find looks for files matching the glob `c*e*`, which matches the `cde` file. Bad, because `cde` does not contain `c*e`.

### File names with extra characters

If you have `abcde` and `abc.part` files, the former will be deleted because it matches `abc*` as should be clear from the previous case discussion.

This particular problem would be easily fixed by changing `$base*` -> `$base.*`.

## Solutions

You only want to operate in the current directory, so why not

    for f in *.part; do
        rm "${f%.part}."*
    done

Here it is crucial **not** to quote the `*`, because we want it to act as a glob (and not literally).

`${f%suffix}` is a special form of [parameter expansion](https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html) available in all POSIX shells. It means "remove `suffix` from the expansion of `f`". It looks cleaner than Basename and doesn't spawn an extra process.

For something more along the lines you suggested,

    find . -maxdepth 1 -name '*.part' -exec sh -c 'rm "$(basename "$1" .part)".*' sh {} \;

But it looks considerably convoluted and `-maxdepth 1` is not a [POSIX specified option to Find](https://pubs.opengroup.org/onlinepubs/9699919799/utilities/find.html), so you are also sacrificing portability. (It is possible to write the POSIX equivalent of `-maxdepth 1` but it adds obscurity.)