CS 497C – Introduction to UNIX Lecture 7: General-Purpose Utilities Chin-Chih Chang

script: Record Your Session If you want to keep track of all your activities, you can invoke the script command after you log in: $ script Script started, file is typescript $ All your keystrokes that you enter get recorded in the file typescript.

script: Record Your Session You can view this file with the cat command. Script overwrites any previous typescript file. To append activities to existing file typescript, use: script -a To log activities to a different log file, use: script logfile

clear and tput: Clear Your Screen There are two commands available in most UNIX systems to clear your screen – clear and tput. The clear command is used without arguments: clear The tput command is used with the clear argument: tput clear

clear and tput: Clear Your Screen tput can als position the cursor at a specific location or be used to highlight text. tput cup You can boldface your text by using the smso and rmso arguments. smso starts highlighting the text and rmso ends highlighting. tput smso echo Come to the Web tput rmso

uname: Know Your Machine’s Name If your machine is connected to the Internet, then your machine name forms part of your machine’s domain name (a series of words separated by dots). Use –n option to show the machine name in a network: $ uname –n sisko Use –r option to show the operating system’s version.

date: Display The System Date The UNIX system maintains an internal clock meant to run perpetually. When the system is shut down, a battery backup keeps the clock ticking. The clock actually stores the number of seconds elapsed since January 1, You can display the current date with the date command.

date: Display The System Date The date command can display specific format by a + symbol followed by the % operator and a single character describing the format: –d – the day of the month (1 to 31) –m – month in the number format (1 to 12) –h – month name –y – the last two digits of the year –H, M, and S – the hour, minute and second, respectively.

date: Display The System Date You can combine them in the format where the + symbol precedes a string which specifies the requested format within a pair of “ symbols. To show the month name, date, and, you can use the following command: $ date +”%h %d %y” Sep 3 01 To change the system date, you need the administrator permission.

cal: The Calender cal is a handy tool that you can invoke anytime to see the calendar of any specific month or a complete year. To show December, use: $ cal dec To show the year of 2002, use: $ cal 2002 | more The | symbol connects two commands (in a pipeline) where more takes input from the cal command.

calendar: A useful Reminder Mechanism The calendar command provides a useful reminder mechanism for a user. The command searches a file named calendar in the current directory $ cat calendar Sep 3 Labor Day Sep 5 Howework Due

calendar: A useful Reminder Mechanism You can use date and calendar in a sequence to show those lines containing today’s and tomorrow’s dates. $ date Mon Sep 3 12:30:14 CDT 2001 $ calendar Sep 3 Labor Day

bc: The Calculator Two types of calculators are available in UNIX – a graphical object (the xcalc command) and the character-based bc command. bc belongs to a family of commands (called filters) that expect input from the keyboard when used without any argument. Key in the following arithmetic expression: $ bc

bc: The Calculator bc added the two numbers and showed the output in the next time. To quit bc, you have to use [Ctrl-d] that marks the end of input. You can also ask bc to perform calculations together: 12*12; 2^

bc: The Calculator By default, bc performs truncated division, and you have to set scale to the number of digits of precision before you perform any division: 9/5 1 scale = 2 17/7 2.42

bc: The Calculator bc is quite useful in converting numbers from one base to another. An example to convert a binary number to a decimal one is shown as follows: ibase=

bc: The Calculator The reverse is possible: obase = You can convert from one base to the another: obase = E

bc: The Calculator bc can be used with variables: x = 3; y = 4; z = 5 p = x + y + z p 12 bc is a pseudo-programming language featuring arrays, functions, conditionals ( if ) and loops ( for and while ). It also comes with a library for performing scientific calculations.

More General Purpose Commands Copy, rename and delete files with cp, mv and rm. View and print a file with cat, more, and lp. Compress a file with compress and gzip. Find out disk space utilization with df and du.

More General Purpose Commands Extract the two ends of a file with head and tail. Cut and past a file with cut and paste. Find differences between two files with comm, cmp, and diff. Sort a file’s contents with sort.