RC

A shell for Unix and Plan 9, written by Tom Duff then of Bell Labs.

rc combines extremely simple syntax with the expressivity and fine-grained control of the Bourne shell (sh).

Examples of parallels between Bourne shell and rc follow:

• if w | grep me; then echo "I'm here!"; fi in Bourne becomes if (w | grep me) echo 'I''m here!' in rc (rc uses C/AWK-like brace-based syntax rather than the keyword-cluttered Algol/Pascal-like syntax of Bourne)
• size = `wc -l \'ls -t|sed 1q\`` in Bourne becomes size = `{wc -l `{ls -t | sed 1q}} in rc (rc only parses its input once, obviating the need to escape the backquotes with a backslash)

Also, rc has support for nonlinear pipelines via pipeline branching: cmp <{old} <{new} runs the commands ``old'' and ``new'', comparing their input.

The syntax and semantics of rc have also spawned an offshoot for Unix only at this point, called es (the ``extensible shell'', which has support for many advanced language features like lambda expressions and lexical scoping).

Abbreviation for 'run commands' - this is the extension used by many Unix configuration files related to starting up the OS or an application, etc.

Reportedly derived from a utility called runcom from CTSS that was used to create scripts

Also an abbreviation for Ron's Code or Rivest Cipher, which is used to prefix cipher algorithms that Ron Rivest comes up with. Currently, RC2, RC4, and RC5/6 are in use. RC1 never made it out of his notebook, and RC3 was broken at RSADSI during development.

RC is also used in relation to drugs where it is the abbreviation of Research Chemical.

Some of the (slightly) more known chemicals that come under this category are 2C-B 2C-T-7 and 5-MeO-DMT

They generally come under the chemical groups of either Phenethylamine or Tryptamine, and for some reason seem to always be full psychedelic drugs, whereas the given description "Research Chemicals literally refers to chemicals that are still being researched" (from erowid.org) implies that any new, non-psychedelic drugs should also fall within this category.

Due to the way the drugs laws worked until recently it was relatively easy to get new research chemicals as they had to be made illegal as each substance was discovered or invented. These laws have recently been changed in most countries, but certain places (including parts of America) still have vendors for these substances. What these new laws did was to make any chemical within a group illegal without each having to be added individually.