>> So, my first question would be, what precisely is it you're trying >> to prevent?
> I want to prevent B to mount something on a temporary mount point > already in use by A. Ah, got it. That's a clear desire and the use case you sketch makes sense to me. I don't think there is anything like this in mount(2), nor, therefore, in mount(8). Certainly not in the versions I'm familiar with. It sounds to me as though cooperative locking is suitable, in which case you might want to use auxiliary lock files. I'd probably do this as something like exec 3>/root/backup/lockfile flock -ex 3 3>&3 ... mount ... /root/backup/tmp-mountpoint ... umount /root/backup/tmp-mountpoint ... Unlock is automatic on script exit; flock -un 3 3>&3 if you want to unlock before exiting flock in the above is a command-line interface to flock(2), which has the advantage over (for example) locking by creating directories in that locks are cleaned up automatically by a reboot. I imagine some people have built their own utility along these lines; in case you're not one such, here's the one I use, as a base64ed bzip2ed .c file: QlpoOTFBWSZTWTMe7MkAAXRfgGgwe//yf37visT/7//+YAOcc77ltnTXQ3bHGTJo xDE0wEDAmmCMExNNNABhBpMpkmaaU/SnpNoE9QxAYCGCZAA0ADIjU01GJqeUNDTQ DQAADQAB6QeoEiJNSMKb1NR5J5JnqT1D1D1GhkND1GjE0D1BocZMmjEMTTAQMCaY IwTE000AGEEkSaAJo1T8kxokeiBiNGgeoGgDEaHqWCQdqoFWG/ue+DsZMxLMvFMn HWCUoSgFDWvimhQz4XruoGK9D/0OY2y/TCWMrFWNPAQWiBKUi1iE0nA2M2fK3Dta cW+0uz8s6JDAFE3Iy5DZU28gOJAL+Aj0hK9UqeiuFOC9LFLlLPAo+hYgVbWd7RfP cMuXGSZL2VJniC0hcedpNO1EGDns7EkWCpNkMOJSmwOiJ6qgDXLYcETF1UmhijOG o2NHygVgJqDNAczJhVh/uvVl7zBFFyDrXMFO1o+d9CudBlR+4EM5ZBLLnj2RuVcX A8m2+Rh63+/ZlOndrhvaprXKjmv0LHeceT3aLeVqjyMITzqRQbu3CcBq7ua+aSQq KFhcEdZojogSFftITIlxl1bNBxQhhtrWfPYQEO2k9xbo36XAU22GD3bG83hYhFDw K8dvc6d0cskilOUKUBjchnBen0ckolg+UINSGZOkOoJx9S+yXWqcI2zZ1h+JHBup LsWtQRuCE1CX6T1JrQ8y2d8PEHJgpkWLo2OX/Nm8gdKnXpn6EbCgGREcpO3nRukt SyphTqu27GFtgWcvBTGRaq/NgWmBDQ7LpFZFTSTEpoZrANQMnVqGs5Z6+rIEMg9D jwKzoQxZI0bcNHwmOAMzMk+pTKg14DZJCXfYQtCM3aVklGv6tDNc4ROyrtr0tY66 4DofAJZngCMG14SriKuw3lSUYLlm4ErTeZ3urHaikkQyzcbKHCOhinOS5EMzBrOJ zKoIgZMwWBQFEaANIkiPYBBagX7E96VTlE4E0idryrLsOK6yabUT1IpjYVM6ImiE qI13NLvB1qRwuisqJ4KM6nklIgDpUNCAEyuHbGcUza7b75+yYDjuRyNgUVauBtO+ isvvdweCHchVjThVYG1EtE7mMJkUuFAW6WRJrHr03woBpAhLOt8gnxkEnFKwc+7L JvWQq5kJd7hMRftZd2zQzH4ESGk40XRUqGhi5mqyEoeQ5AaMLAQFCPIcTfSFboSk MhZXxI13E1FGc7lc8R4kjJKVlAuZVNeljErmVmBNzjHKzC6QgRSUqEk/8XckU4UJ AzHuzJA= /~\ The ASCII Mouse \ / Ribbon Campaign X Against HTML [email protected] / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B
