login: myname password:(not echoed)In Unix, once you have logged on you will be running a program called a "shell". The shell is your interface to the operating system. A shell prints a prompt (below, the prompt is "%") when it is ready for a command. All commands are terminated by a carriage return. More about the shell later.
% yppasswdyppasswd will prompt you for your old password, and then ask you to enter your new one twice (to forestall mistakes). For your own security, you should try and choose a password that is not easily guessable. Here's some helpful guidelines:
% cd /bin % cd /usr/include % cdThe first example moves you to the system binaries directory. The third example moves you to your home directory, where you can store your own files.
% cd sys % cd ..In the first example, we moved into the sys subdirectory of the current directory. In the second example, we moved to the "parent" directory (the directory that your current directory is a subdirectory of).
% cd /var/spool % cd .. % pwd /var
% cd /var/spool % ls calendar lpd mqueue secretmail cron lpd.lock printers uucp locks mail rwho uucppublicTo display more information about the files in the directory, type "ls -l" instead:
% ls -l total 31 drwxrwsrwt 2 daemon 6656 Sep 2 04:04 calendar drwxr-sr-x 4 root 512 Aug 16 10:00 cron drwxr-sr-x 2 uucp 512 Jul 26 12:13 locks drwxrwsr-x 2 daemon 512 Jul 26 1995 lpd -rw-r--r-- 1 root 4 Aug 16 10:00 lpd.lock drwxrwsrwt 2 root 4608 Sep 2 16:39 mail drwxr-s--- 2 root 9728 Sep 2 16:39 mqueue lrwxrwxrwx 1 root 22 Jul 26 1995 printers -> /export/spool/printers drwxr-sr-x 2 root 512 Oct 14 1994 rwho drwxrwsrwx 2 bin 512 Oct 14 1994 secretmail drwxr-sr-x 10 uucp 512 Aug 16 10:00 uucp drwxrwsrwt 2 uucp 512 Oct 14 1994 uucppublic
% cd % mkdir games
% cd $HOME/games % rm * % cd .. % rmdir gamesNote that if you are using the (t)csh shell, the tilde character ~ is a shortcut for $HOME, your home directory. Hence the following are equivalent:
% cd % cd ~/ % cd $HOMESimilarly the following are equivalent:
% cd ~/bin % cd $HOME/bin
cp source_file destinationSome examples:
% cp /etc/holidays myfile % cp myfile myfile-oldThe first example copies the file holidays in the directory /etc into the file myfile in the current directory.
mv source destinationYou can use this to move a file, or to rename it:
% mv myfile-old myfile.old % mv myfile.old backups/myfile.oldThe first example renames myfile-old so it is now named myfile.old. The second example moves myfile.old into the backups/ directory.
rm file_to_be_removedUse this command to delete files you don't want:
% rm random.file
% cat myfile (displays contents of myfile)
% more myfile"More" allows you to read a file page by page. While viewing the file, the basic commands are space to see the next page, q to quit, return to see one more line, and b to go back a page.
% cp /bin/ls myls % mylsSometimes you may run into a program that will not quit, or is stuck in an endless loop, and is tying up the shell. To abort the program, just type Ctrl-C while in the shell that is executing the program. This should cause the program to terminate.
If for some reason when trying to run some program you get:
% programbin programbin: Permission denied.you can correct the problem by changing the file permissions to execute:
% chmod u+x programbin
man command man -k keyword apropos keywordman gives you information about specific commands. man -k tells you what commands relate to a given keyword.
% man -k sqrt cbrt sqrt (3m) - square root, cube root sqrt sqrt (3m) - square root, cube root sqrt cplxexp (3) - functions in the C++ complex number math libraryThe number in parentheses refers to the chapter of the manual in which the command is listed.
% man BattleTrisIf you are working on a X-Windows environment (ie. you are logged on from a workstation or an X-terminal, you can also try xman for a graphical interface to the man pages:
% xman &The "&" at the end of the previous line is used to run the "xman" process in the background and give you back control over your shell.