Hacker News new | past | comments | ask | show | jobs | submit login

Can someone please elaborate as to why this works? I'm unable to understand how in hell Bash turns this PoC into "date>echo".

rm -f echo && <---- Irrelevant, removes old echo files.

env -i X=' <---- Start definition of an environment variable. () { <---- Function definition which is expected by the parser according to the codebase. (a)= <---- I have no idea what this [1] is or [2] does. >\ <---- I have no Idea what this [3] is but kinda know what it does. Executing ">\echo date" in a bash term somehow yields same result as "date > echo". Is this a feature? [4] Does bash have a ">\" operator? [5]

' bash -c 'echo date'; cat echo <----- End the environment variable definition, run a new shell so that the vars get loaded and output the contents of the file "echo" if created.

I would really appreciate anyone shedding some light on [1]...[5].




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: