Index[SYMBOL] [A] [B] [C] [D] [E] [F] [G] [H] [I] [J] [K] [L] [M] [N] [O] [P] [R] [S] [T] [U] [V] [W] [X] [Y] [Z] $ end-of-line regular expression $PWD environment variable $USER environment variable & (ampersand) running applications in background running background processes * (asterisk) regular expression 2nd -F option -f option (rm command) -geometry command -R option -r option (rm command) . (period) dot files . (period) regular expression 2nd .dvi extension .ps extension .rhosts file .tr extension .xinitrc file 2nd creating 2nd 3rd 4th 5th name variations [] (brackets) 2nd [] (brackets) regular expressions ^ start-of-line regular expression | (pipe) 2nd ~ (tilde) home directory 2 operator 3 operator |