cal , display a calendar cat, concatenate and display cc , C compiler cd , change working directory chmod, change the permissions mode of a file cmp , perform a byte-by-byte comparison of two files comm , display lines in common;and lines not in common;between two sorted lists cp , copy files csh , a shell (command interpreter) with a C-like syntax and advancedinteractive features diff , display line-by-line differences between pairs of text files du , display the number of disk blocks used per directory or file echo , echo arguments to the standard output ed;red, basic line editor ex;edit;e line editor find , find files by name;or by other characteristics finger, display information about users ftp , file transfer program grep, search a file for a string or regular expression history , re-use previous command lines kill , send a signal to a process;or terminate a process ld;ld.so , link editor;dynamic link editor less , opposite of more login, log in to the system lp;cancel send/cancel requests to a printer ls, list the contents of a directory make , maintain;update;and regenerate related programs and files man , display reference manual pages; find reference pages by keyword mkdir, make a directory more;page ,move or rename files passwd, change local or NIS password information printenv , display environment variables currently set ps , display the status of current processes pwd , display the pathname of the current working directory rm;rmdir, remove (unlink) files or directories rwho, who's logged in on local machines sh , shell;the standard UNIX system command interpreter and command, level language size, display the size of an object file tail, display the last part of a file tar, create tape archives;and add or extract files telnet , user interface to a remote system using the TELNET protocol vi, display a count of lines;words and characters whatis - display a whereis , locate the binary;source;and manual page files for a command which , locate a command; display its pathname or alias who , who is logged in on the system whoami , display the effective current username