curl not able to write to /tmp directory owned by user

I tried running the script as instructed in https://docs.docker.com/engine/security/rootless/ : $ curl -fsSL https://get.docker.com/rootless | sh But the script crashed in the following line: curl -L -o docker.tgz "$STATIC_RELEASE_URL" With the message: Warning: Failed to create the file docker.tgz: Permission denied curl: (23) Failure writing output to destination I narrowed down the problem to curl trying to write to the tmp folder created by mktemp -d, but I don't understand why it fails. Some context: $ whoami thiago $ uname -a Linux thiago-acer 5.8.0-55-generic #62~20.04.1-Ubuntu SMP Wed Jun 2 08:55:04 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux $ mktemp -d /tmp/tmp.U1nPTN5dlS $ cd /tmp/tmp.U1nPTN5dlS $ ls -la total 8 drwx------ 2 thiago thiago 4096 Jun 17 18:20 . drwxrwxrwt 25 root root 4096 Jun 17 18:20 .. After running the commands above, I tried: # this fails with the same message as above curl https://download.docker.com/linux/static/stable/x86_64/docker-20.10.7.tgz -O # this works just fine curl https://download.docker.com/linux/static/stable/x86_64/docker-20.10.7.tgz -o - > docker-20.10.7.tgz # this also works wget https://download.docker.com/linux/static/stable/x86_64/docker-20.10.7.tgz The curl -O command also works if I try it on some other folder, like my home folder. Any help is appreciated.