3 ms·

This one made me LOL: My mistake on SunOS (with OpenWindows) was to try and clean up all the '.' directories in /tmp. Obviously "rm -rf /tmp/" missed t

This one made me LOL: My mistake on SunOS (with OpenWindows) was to try and clean up all the '.*' directories in /tmp. Obviously "rm -rf /tmp/*" missed these, so I was very careful and made sure I was in /tmp and then executed "rm -rf ./.*". I will never do this again. If I am in any doubt as to how a wildcard will expand I will echo it first. I read this, and just had to go try it because I couldn't picture it in my brain. Here it is: $ echo ./.* ./. ./.. So if you're in /tmp/ and do 'rm -rf ./.*', it's rm -rf ./. ./.. and ./.. is .. which from tmp is /. Thankfully we have protections against this now. Back then, not so much.

yjftsjthsd-h 5y ago
Huh, what do you know. I thought modern rm only protected against deleting / by absolute path, but it looks like it'll protect you from deleting your parent regardless: $ docker run --rm -ti debian:11 # sandbox the danger... root@c70dde9f38a3:/# cd /tmp root@c70dde9f38a3:/tmp# rm -rf ./. rm: refusing to remove '.' or '..' directory: skipping './.' root@c70dde9f38a3:/tmp# mkdir -p /tmp/1/2/3/4/5 root@c70dde9f38a3:/tmp# cd /tmp/1/2/3/4/5 root@c70dde9f38a3:/tmp/1/2/3/4/5# rm -rf ./. rm: refusing to remove '.' or '..' directory: skipping './.'
simonblack 5y ago
As a brand-new UNIX user around 1991 and coming from MSDOS, I was used to being 'God' on my machine so I thought it would be a good idea to login always as 'root'. I couldn't understand why long-time users of UNIX knew that to be a very bad idea, and always advised against it. Like the SunOS person, I had lots of dot-directories in /tmp. So I duplicated his actions almost perfectly. Also like he did, I was wondering why an 'instantaneous' action was taking so long. I had to do a complete re-installation. Ever since then, I've always logged in as a 'normal user'. My reign as 'God' in a UNIX environment lasted about 2-3 weeks in total.
lsh123 5y ago
Actually this is exactly what Oracle installer did in 93-94 after a jr sysadmin tried to install it from /tmp.
tomlx 5y ago
Interestingly $ bash -c 'cd /var/empty; echo .*' . .. but $ ksh -c 'cd /var/empty; echo .*' .* Seems some ksh dev got bitten and restricted this ...

This one made me LOL: My mistake on SunOS (with OpenWindows) was to try and clean up all the '.*' directories in /tmp. Obviously "rm -rf /tmp/*" missed t

yjftsjthsd-h 5y ago

Huh, what do you know. I thought modern rm only protected against deleting / by absolute path, but it looks like it'll protect you from deleting your parent regardless: $ docker run --rm -ti debian:11 # sandbox the danger... root@c70dde9f38a3:/# cd /tmp root@c70dde9f38a3:/tmp# rm -rf ./. rm: refusing to remove '.' or '..' directory: skipping './.' root@c70dde9f38a3:/tmp# mkdir -p /tmp/1/2/3/4/5 root@c70dde9f38a3:/tmp# cd /tmp/1/2/3/4/5 root@c70dde9f38a3:/tmp/1/2/3/4/5# rm -rf ./. rm: refusing to remove '.' or '..' directory: skipping './.'

simonblack 5y ago

As a brand-new UNIX user around 1991 and coming from MSDOS, I was used to being 'God' on my machine so I thought it would be a good idea to login always as 'root'. I couldn't understand why long-time users of UNIX knew that to be a very bad idea, and always advised against it. Like the SunOS person, I had lots of dot-directories in /tmp. So I duplicated his actions almost perfectly. Also like he did, I was wondering why an 'instantaneous' action was taking so long. I had to do a complete re-installation. Ever since then, I've always logged in as a 'normal user'. My reign as 'God' in a UNIX environment lasted about 2-3 weeks in total.

lsh123 5y ago

Actually this is exactly what Oracle installer did in 93-94 after a jr sysadmin tried to install it from /tmp.

tomlx 5y ago

Interestingly $ bash -c 'cd /var/empty; echo .*' . .. but $ ksh -c 'cd /var/empty; echo .*' .* Seems some ksh dev got bitten and restricted this ...