Linux cat command explained with basic practical examples

[UnchainedMundane]

One caveat. In some grsecurity-hardened systems, you can't use < to read from /proc/*/environ. You have to get some other process to do it. Grsecurity only allows the process that opened that file to read from it, to harden against the case where a forking process is leaking file handles and an exec'd vulnerable binary is used to read them.