The reason this occurs is because bash actually expands the asterisk to every matching file, producing a very long command line.
Try this:
find . -name “*.pdf” -print0 | xargs -0 rm
Warning: this is a recursive search and will find (and delete) files in subdirectories as well. Tack on -f to the rm command only if you are sure you don’t want confirmation.
You can do the following to make the command non-recursive:
find . -maxdepth 1 -name “*.pdf” -print0 | xargs -0 rm
Another option is to use find’s -delete flag:
find . -name “*.pdf” -delete
tl;dr
It’s a kernel limitation on the size of the command line argument. Use a for loop instead.
Origin of problem
This is a system issue, related to execve and ARG_MAX constant. There is plenty of documentation about that (see man execve, debian’s wiki).
Basically, the expansion produce a command (with its parameters) that exceeds the ARG_MAX limit.
On kernel 2.6.23, the limit was set at 128 kB. This constant has been increased and you can get its value by executing:
getconf ARG_MAX
# 2097152 # on 3.5.0-40-generic
Solution: Using for Loop
Use a for loop as it’s recommended on BashFAQ/095 and there is no limit except for RAM/memory space:
Dry run to ascertain it will delete what you expect:
for f in *.pdf; do echo rm “$f”; done
And execute it:
for f in *.pdf; do rm “$f”; done
Also this is a portable approach as glob have strong and consistant behavior among shells (part of POSIX spec).
Note: As noted by several comments, this is indeed slower but more maintainable as it can adapt more complex scenarios, e.g. where one want to do more than just one action.
Solution: Using find
If you insist, you can use find but really don’t use xargs as it “is dangerous (broken, exploitable, etc.) when reading non-NUL-delimited input”:
find . -maxdepth 1 -name ‘*.pdf’ -delete
Using -maxdepth 1 … -delete instead of -exec rm {} + allows find to simply execute the required system calls itself without using an external process, hence faster (thanks to @chepner comment).
References
I’m getting “Argument list too long”. How can I process a large list in chunks? @ wooledge
execve(2) – Linux man page (search for ARG_MAX) ;
Error: Argument list too long @ Debian’s wiki ;
Why do I get “/bin/sh: Argument list too long” when passing quoted arguments? @ SuperUser