5 ms·

About 25 years ago I saw somebody do a "chmod a-rwx ." as root, at root on an SunOs box. Recovering from that was almost entertaining ;-)

fjarlq 12y ago
But the superuser privileges should have overridden such directory permissions, even 25 years ago....
- DmitriRavinoff 12y ago
  Yes, but if you can't run the chmod binary...
  - fjarlq 12y ago
    No, root can still run chmod, because its superuser privileges override the new restrictive directory perms. That was my point. Maybe the original problem was actually "chmod a-rwx /bin/chmod" ... That would mean even the superuser couldn't execute /bin/chmod anymore, so you'd have to do something more creative to reset the executable bit on /bin/chmod. Like compile a C program that calls the chmod system call, or: mv /bin/chmod /bin/chmod.orig cp -p /bin/ls /bin/chmod cp /bin/chmod.orig /bin/chmod
    - pantalaimon 12y ago
      > Like compile a C program that calls the chmod system call The compiler wouldn't be executable anymore either
      - claviola 12y ago
        Yes, it would. Like he said, you can still run it unless you specifically removed its permissions.
  - mtdewcmu 12y ago
    The explanation for what made him type that is what interests me. It would be like accidentally cutting your left hand clean off with a steak knife while you were eating dinner.
    - johnchristopher 12y ago
      My bash is set to use vim bindings (set -o vi) and I constantly loop through commands. I am guilty of doing this while sleepy and sometimes I think I have cd to another directory when in fact I have not. I rm-ed (too) many things that way.
      - mtdewcmu 12y ago
        I gave the vi mode a very short try, but it doesn't seem to make as much sense in a shell. If it has you accidentally deleting things, you might want to ask how much is it really worth. In vim you can undo.
  - r4um 12y ago
    One can use the shared library loader to invoke binaries that do not have executable bit set, comes in handy once in a while. $ cp /bin/chmod . $ chmod -x ./chmod $ /lib/ld-2.19.so ./chmod ./chmod: missing operand Try './chmod --help' for more information.
ibisum 12y ago
Oh, the pain! I remember doing that 25 years ago too, ouch.
pbhjpbhj 12y ago
My worst has been accidentally removing zip - back in my Slackware days IIRC. I was trying to upgrade and so I removed the old one and then went to install the new one and couldn't install it again as the packager used zip and all the downloads I could find were tar.gz (or tar.bz2 or whatever). That was the first, and last time I think, that I used cpio. Phew.
pbhjpbhj 12y ago
My worst has been accidentally removing zip - back in my Slackware days IIRC. I was trying to upgrade and so I removed the old one and then went to install the new one and couldn't install it again as the packager used zip and all the downloads I could find were tar.gz (or tar.bz2 or whatever). That was the first, and last time I think, that I used cpio.
onthedole 12y ago
A few years ago I changed over from a Dell PC Keyboard to an Apple keyboard. I had to delete some files in a temp folder and typed the command as I was always used to, and pressed enter. Immediately realised something was wrong and then saw the "*" replaced with a "/". Did not have a fun afternoon. http://i.imgur.com/4k4SOpF.jpg http://i.imgur.com/4k4SOpF.jpg

fjarlq 12y ago

But the superuser privileges should have overridden such directory permissions, even 25 years ago....

DmitriRavinoff 12y ago
Yes, but if you can't run the chmod binary...
- fjarlq 12y ago
  No, root can still run chmod, because its superuser privileges override the new restrictive directory perms. That was my point. Maybe the original problem was actually "chmod a-rwx /bin/chmod" ... That would mean even the superuser couldn't execute /bin/chmod anymore, so you'd have to do something more creative to reset the executable bit on /bin/chmod. Like compile a C program that calls the chmod system call, or: mv /bin/chmod /bin/chmod.orig cp -p /bin/ls /bin/chmod cp /bin/chmod.orig /bin/chmod
  - pantalaimon 12y ago
    > Like compile a C program that calls the chmod system call The compiler wouldn't be executable anymore either
    - claviola 12y ago
      Yes, it would. Like he said, you can still run it unless you specifically removed its permissions.
- mtdewcmu 12y ago
  The explanation for what made him type that is what interests me. It would be like accidentally cutting your left hand clean off with a steak knife while you were eating dinner.
  - johnchristopher 12y ago
    My bash is set to use vim bindings (set -o vi) and I constantly loop through commands. I am guilty of doing this while sleepy and sometimes I think I have cd to another directory when in fact I have not. I rm-ed (too) many things that way.
    - mtdewcmu 12y ago
      I gave the vi mode a very short try, but it doesn't seem to make as much sense in a shell. If it has you accidentally deleting things, you might want to ask how much is it really worth. In vim you can undo.
- r4um 12y ago
  One can use the shared library loader to invoke binaries that do not have executable bit set, comes in handy once in a while. $ cp /bin/chmod . $ chmod -x ./chmod $ /lib/ld-2.19.so ./chmod ./chmod: missing operand Try './chmod --help' for more information.

ibisum 12y ago

Oh, the pain! I remember doing that 25 years ago too, ouch.

pbhjpbhj 12y ago

My worst has been accidentally removing zip - back in my Slackware days IIRC. I was trying to upgrade and so I removed the old one and then went to install the new one and couldn't install it again as the packager used zip and all the downloads I could find were tar.gz (or tar.bz2 or whatever). That was the first, and last time I think, that I used cpio. Phew.

pbhjpbhj 12y ago

onthedole 12y ago

A few years ago I changed over from a Dell PC Keyboard to an Apple keyboard. I had to delete some files in a temp folder and typed the command as I was always used to, and pressed enter. Immediately realised something was wrong and then saw the "*" replaced with a "/". Did not have a fun afternoon. http://i.imgur.com/4k4SOpF.jpg http://i.imgur.com/4k4SOpF.jpg