McEs, A Hacker Life: Linux Shell Puzzle

Thursday, September 06, 2007

Linux Shell Puzzle

Write a shell script named pchdir that when run like pchdir /bin it will change the current directory of its parrent process to /bin.

Labels: linux, puzzle, shell

¶ 1:56 AM

Comments:

Sorry, Behdad, try harder:

----------------
#!/bin/bash

pid="$PPID"
cwd="$1" # first argument is the CWD, there is a quoting bug below but I really couldn't care less

gdb -q << EOF
attach $pid
call (int) chdir("$cwd")
detach
quit
EOF
---------------

Bash is my bitch.

# posted by

Anonymous : September 06, 2007 3:47 AM

Just for completeness.

# posted by

Anonymous : September 06, 2007 3:58 AM

Ok, you got this one. This is my version:

#!/bin/bash
gdb /proc/$PPID/exe $PPID <<<"p chdir(\"$1\")" &>/dev/null

# posted by

behdad : September 06, 2007 2:38 PM

I may have beat you in speed, but you rightly pwn me in onelined-ness!

Hats off :-) And all the good in the world to anything that lets us unmount our /homes when stuff is still running!

# posted by

Anonymous : September 13, 2007 12:19 AM

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