This book is designed to be a shell programmer's reference on Unix and Linux. It covers the commands, syntax, and operators for three major shells used in Unix and Linux; the Bourne Again shell (BASH), the TCSH shell, and the Z-shell. All are enhanced versions of their corresponding original Unix shells. The BASH shell is an advanced version of the Bourne shell, which includes most of the advanced features developed for the Unix Korn shell and C-shells. TCSH is an enhanced version of the C-shell that was originally developed for BSD versions of Unix. The Z-shell is an enhanced version of the Unix Korn shell. The Perl and GAWK shell scripting languages are also presented in detail, examining the use of variables, operators, and control structures to create complex shell programs. In addition the book covers supplementary features like the Make utility and man page formatting.