2019.09.17.pdf - Announcements ‣ Ideas on Tap •AI in the Western Canadian Software Industry •16:00 – 19:00 Friday Sept 27 •Vendasta •The

2019.09.17.pdf - Announcements ‣ Ideas on Tap •AI in...

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Announcements Ideas on Tap •AI in the Western Canadian Software Industry •16:00 – 19:00, Friday, Sept 27 •Vendasta •The Avenue Building, Innovation Place #405 - 220 3rd Avenue South 1
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Announcements Student Learning Services •example course: "Study Strategies for Academic Success" •17:00 – 17:50, Thursday, Sept 19 •see listEvents?currentSystemId=1 for list of events 2
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Announcements Computer Science Fall Programming Contest •Saturday, Sept 28 •09:00 – 16:00 •3rd floor Spinks Addition •contact [email protected] •free registration … and free pizza! 3
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Quote of the Day 4 If the designers of X-Windows built cars, there would be no fewer than five steering wheels hidden about the cockpit, none of which followed the same principles -- but you'd be able to shift gears with your car stereo. Useful feature, that. •Marcus J. Ranum
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review 5
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6 File Permissions chmod •to change file permissions can use chmod symbolic-mode - e.g. chmod g+w temp chmod o-rwx temp chmod a+r temp chmod a+rwx temp chmod o=r temp can use chmod mask where mask is a bit pattern in octal - e.g. chmod 764 temp •see pp. 102–104, 759–763 of Sobell text
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File Permission and Directories 7 special interpretation for directories "r" permission •whether you can read what files are in a directory "w" permission •whether you can add or remove files to/from a directory "x" permission •sometimes referred to as "search permission" •whether you can lookup a pathname of a file within the directory also whether you can cd to the directory
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On to today's material … 8
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Controlling Ownership chgrp •change group ownership usage chgrp groupname file chown •chown owner of a file •typically a restricted command for security and sys admin reasons note: typically on lab machines, students are restricted in ability to change file ownership 9
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File Types basic types: ordinary files, directories other types how to determine the type of an ordinary file? especially since extensions are not required file command makes use of “magic pattern” information, typically at the beginning of the file -man magic •Sobell, pp. 60, 820–821 •see example 10
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Pattern-Matching in Filenames * match any number of any characters ? match any one character [] match one of a set of characters others N.B.: supported by shell, and not file system nor application program 11
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More Commands Related to Files more , less 53, 873–876 diff , cmp 59, 795–799 wc 1027 sort 58, 969–977 uniq 58, 1023–1024 head , tail 57, 861–862, 992–994 du 809–811 df 793–794 12 Page(s) in Sobell text: are identical shows additions and deletions between files word count, lines etc checks if things are sorted, sorts, sort -r randomizes checks sorted file for unique or repeated lines head gives first "n" lines tail gives last "n" lines tells disk usage for file or dir
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More Commands Related to Files example 13
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Reminder 14 Practise this stuff!!!
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