find exec rm: No such file or directory - linux

Question

Why "No such file or directory" in example below?
There are workarounds to not get this error, the question is why in this exact example the error is produced.
cd /tmp
mkdir -p TOP1/AB/AC/AD/AE/AF
mkdir -p TOP2/AB/AC/AD/AE/AF
find . -iname 'A*' -exec rm -rvf {} \;
removed directory: `./TOP1/AB/AC/AD/AE/AF'
removed directory: `./TOP1/AB/AC/AD/AE'
removed directory: `./TOP1/AB/AC/AD'
removed directory: `./TOP1/AB/AC'
removed directory: `./TOP1/AB'
find: `./TOP1/AB': No such file or directory
removed directory: `./TOP2/AB/AC/AD/AE/AF'
removed directory: `./TOP2/AB/AC/AD/AE'
removed directory: `./TOP2/AB/AC/AD'
removed directory: `./TOP2/AB/AC'
removed directory: `./TOP2/AB'
find: `./TOP2/AB': No such file or directory
Using -depth or \+ or -delete fix this issue:
find . -iname 'A*' -exec rm -rvf {} \+
find . -depth -iname 'A*' -exec rm -rvf {} \;
find . -iname 'A*' -delete

Answer 1

I think the answer is in the man page itself: https://linux.die.net/man/1/find
Also see \; vs +: Using semicolon (;) vs plus (+) with exec in find
To understand the whole process better, you can print the files instead of deleting them. Considering the TOP1 folder for example:
find . -iname 'A*' -exec echo "{}" \;
Output:
./TOP1/AB
./TOP1/AB/AC
./TOP1/AB/AC/AD
./TOP1/AB/AC/AD/AE
./TOP1/AB/AC/AD/AE/AF
What \; does is: Run file on every file in or below the current directory.
The order is important here, i.e. first the parent folder is treated, and then its child folders are recursively traversed.
On the other hand, this is how rm -frv works:
rm -frv ./TOP1
Output:
removed directory './TOP1/AB/AC/AD/AE/AF'
removed directory './TOP1/AB/AC/AD/AE'
removed directory './TOP1/AB/AC/AD'
removed directory './TOP1/AB/AC'
removed directory './TOP1/AB'
removed directory './TOP1'
So rm -fr works practically the other way round than find, which is the main cause of the problem here:
find together with \; first starts with the parent folder TOP1, where the folder TOP1 and its contents will be completely deleted thanks to the part -exec rm -rvf {} \;. On the next round find then will try to handle the next child folder below, where it apparently first checks (via stat ./TOP1), if the base folder still exists, and it only then goes one level deeper. But since ./TOP1 was already deleted in the first round, stat ./TOP1 will fail, hence the error message.
With the other parameters available for the find you can obviously change the default behavior:
-depth: Process each directory's contents before the (parent) directory itself. The -delete action also implies -depth. (i.e. treversing from very bottom to top - just like rm -fr does!)
-delete: Use of -delete automatically turns on the -depth option
Using +: the -exec rm -rvf {} + part is executed only once, e.g. -exec rm -rvf {} +:
rm -frv ./TOP1/AB ./TOP1/AB/AC ./TOP1/AB/AC/AD ./TOP1/AB/AC/AD/AE ./TOP1/AB/AC/AD/AE/AF
Last but not least:
When rm is used with the -fr parameter, it becomes very "tolerant", so, no error is thrown. It will try to forcibly and recursively delete everything that is passed to it; and, if it encounters files/directories that do not exist, it will not complain as well.

Answer 2

This is an implementation detail of find. You'll find the ultimate answer to your question in it's source code.
On Linux another way to understand what is happening behind the scenes is strace. I've prepared some interesting output from strace below. You may have a look at the order of the openat system calls issues by both find invocations (with and without -depth):
mkdir -pv TOP{1,2}/AB/AC/AD/AE/AF && strace -o foo find . -depth -iname 'A*' -exec rm -rvf {} \; ; grep openat foo
mkdir: created directory 'TOP1/AB'
mkdir: created directory 'TOP1/AB/AC'
mkdir: created directory 'TOP1/AB/AC/AD'
mkdir: created directory 'TOP1/AB/AC/AD/AE'
mkdir: created directory 'TOP1/AB/AC/AD/AE/AF'
mkdir: created directory 'TOP2/AB'
mkdir: created directory 'TOP2/AB/AC'
mkdir: created directory 'TOP2/AB/AC/AD'
mkdir: created directory 'TOP2/AB/AC/AD/AE'
mkdir: created directory 'TOP2/AB/AC/AD/AE/AF'
removed directory './TOP1/AB/AC/AD/AE/AF'
removed directory './TOP1/AB/AC/AD/AE'
removed directory './TOP1/AB/AC/AD'
removed directory './TOP1/AB/AC'
removed directory './TOP1/AB'
removed directory './TOP2/AB/AC/AD/AE/AF'
removed directory './TOP2/AB/AC/AD/AE'
removed directory './TOP2/AB/AC/AD'
removed directory './TOP2/AB/AC'
removed directory './TOP2/AB'
5:openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
9:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libselinux.so.1", O_RDONLY|O_CLOEXEC) = 3
20:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libm.so.6", O_RDONLY|O_CLOEXEC) = 3
28:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
44:openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libpcre2-8.so.0", O_RDONLY|O_CLOEXEC) = 3
52:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3
60:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
93:openat(AT_FDCWD, "/proc/filesystems", O_RDONLY|O_CLOEXEC) = 3
99:openat(AT_FDCWD, ".", O_RDONLY|O_CLOEXEC) = 3
102:openat(AT_FDCWD, "/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 4
106:openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache", O_RDONLY) = 4
114:openat(AT_FDCWD, ".", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 4
125:openat(5, "TOP1", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
137:openat(7, "AB", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
149:openat(8, "AC", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
161:openat(9, "AD", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
173:openat(10, "AE", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
186:openat(11, "AF", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
223:openat(8, "..", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
231:openat(5, "..", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
237:openat(6, "TOP2", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
249:openat(7, "AB", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
261:openat(8, "AC", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
273:openat(9, "AD", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
285:openat(10, "AE", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
298:openat(11, "AF", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
332:openat(8, "..", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 5
340:openat(5, "..", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
mkdir -pv TOP{1,2}/AB/AC/AD/AE/AF && strace -o foo find . -iname 'A*' -exec rm -rvf {} \; ; grep openat foo
mkdir: created directory 'TOP1/AB'
mkdir: created directory 'TOP1/AB/AC'
mkdir: created directory 'TOP1/AB/AC/AD'
mkdir: created directory 'TOP1/AB/AC/AD/AE'
mkdir: created directory 'TOP1/AB/AC/AD/AE/AF'
mkdir: created directory 'TOP2/AB'
mkdir: created directory 'TOP2/AB/AC'
mkdir: created directory 'TOP2/AB/AC/AD'
mkdir: created directory 'TOP2/AB/AC/AD/AE'
mkdir: created directory 'TOP2/AB/AC/AD/AE/AF'
removed directory './TOP1/AB/AC/AD/AE/AF'
removed directory './TOP1/AB/AC/AD/AE'
removed directory './TOP1/AB/AC/AD'
removed directory './TOP1/AB/AC'
removed directory './TOP1/AB'
find: ‘./TOP1/AB’: No such file or directory
removed directory './TOP2/AB/AC/AD/AE/AF'
removed directory './TOP2/AB/AC/AD/AE'
removed directory './TOP2/AB/AC/AD'
removed directory './TOP2/AB/AC'
removed directory './TOP2/AB'
find: ‘./TOP2/AB’: No such file or directory
5:openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
9:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libselinux.so.1", O_RDONLY|O_CLOEXEC) = 3
20:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libm.so.6", O_RDONLY|O_CLOEXEC) = 3
28:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
44:openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/libpcre2-8.so.0", O_RDONLY|O_CLOEXEC) = 3
52:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libdl.so.2", O_RDONLY|O_CLOEXEC) = 3
60:openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libpthread.so.0", O_RDONLY|O_CLOEXEC) = 3
93:openat(AT_FDCWD, "/proc/filesystems", O_RDONLY|O_CLOEXEC) = 3
99:openat(AT_FDCWD, ".", O_RDONLY|O_CLOEXEC) = 3
102:openat(AT_FDCWD, "/usr/lib/locale/locale-archive", O_RDONLY|O_CLOEXEC) = 4
106:openat(AT_FDCWD, "/usr/lib/x86_64-linux-gnu/gconv/gconv-modules.cache", O_RDONLY) = 4
114:openat(AT_FDCWD, ".", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 4
125:openat(5, "TOP1", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
142:openat(7, "AB", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = -1 ENOENT (No such file or directory)
143:openat(AT_FDCWD, "/usr/share/locale/locale.alias", O_RDONLY|O_CLOEXEC) = 6
148:openat(AT_FDCWD, "/usr/share/locale/en_US/LC_MESSAGES/findutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
149:openat(AT_FDCWD, "/usr/share/locale/en/LC_MESSAGES/findutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
150:openat(AT_FDCWD, "/usr/share/locale-langpack/en_US/LC_MESSAGES/findutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
151:openat(AT_FDCWD, "/usr/share/locale-langpack/en/LC_MESSAGES/findutils.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
154:openat(AT_FDCWD, "/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
155:openat(AT_FDCWD, "/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
156:openat(AT_FDCWD, "/usr/share/locale-langpack/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
157:openat(AT_FDCWD, "/usr/share/locale-langpack/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
164:openat(5, "TOP2", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = 6
179:openat(7, "AB", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW|O_CLOEXEC|O_DIRECTORY) = -1 ENOENT (No such file or directory)