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For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
Some Linux and Unix tips

How to make a woman equal to a man

[trainee@easterton ~]$ man ls
[trainee@easterton ~]$ woman ls
-bash: woman: command not found
[trainee@easterton ~]$ alias woman=man
[trainee@easterton ~]$ woman ls
[trainee@easterton ~]$


In Linux and Unix, the man command gives you a manual page ... but there is no woman command. If you want to be politically correct, you can use alias to make woman equal to man

How big are my files v how big are my directories

[trainee@easterton jimbo]$ du -sk *
64244 httpd-2.0.63
5776 httpd-2.0.63.tar.gz
8 MyJava.class
8 MyJava.java
8 newfile
8 RevTempconv.java
15268 tomcat-connectors-1.2.26-src
1420 tomcat-connectors-1.2.26-src.tar.gz
[trainee@easterton jimbo]$ ls -l
total 7244
drwxr-xr-x 12 jimbo apache 4096 Apr 24 2008 httpd-2.0.63
-rw-r--r-- 1 root root 5896358 Apr 24 2008 httpd-2.0.63.tar.gz
-rw-r--r-- 1 jimbo apache 430 Apr 24 2008 MyJava.class
-rw-r--r-- 1 jimbo apache 115 Apr 24 2008 MyJava.java
-rw-r--r-- 1 jimbo apache 6 Apr 23 2008 newfile
-rw-r--r-- 1 root root 1557 Apr 24 2008 RevTempconv.java
drwxr-xr-x 9 jimbo apache 4096 Dec 21 2007 tomcat-connectors-1.2.26-src
-rw-r--r-- 1 root root 1442605 Apr 25 2008 tomcat-connectors-1.2.26-src.tar.gz
[trainee@easterton jimbo]$


The ls command reports on the size of each symbol in a directory, whereas the du reports on the size of each symbol and what it contains. This means that you should use du if you want to see how much a director contains, but ls if you're just interested in the size of the directory's header records!

Moving files and directories with multiple owners

[root@easterton ~]# cd /home
[root@easterton home]# mkdir ../gosh
[root@easterton home]# tar cf - | (cd ../gosh; tar xpf -)
[root@easterton home]# tar cf - cloudy dave gordon| (cd ../gosh; tar xpf -)
[root@easterton home]# ls -l ../gosh
total 32
drwxr-xr-x 2 cloudy apache 4096 Nov 6 18:09 cloudy
drwxr-xr-x 4 dave dave 4096 Jun 24 10:07 dave
drwxr-xr-x 3 gordon apache 4096 Nov 18 14:02 gordon
[root@easterton home]#


If you're moving a part of your file system around on a Unix or Linux system, you might be inclined to use cp -r and indeed that will work well if you want the ownership of the copy transferred to the user making the copy. But if you want to copy a part of the file tree and preserver ownership, you must to so as root, and use the tar command. In the example above, we have output from tar so stdout, then piped into another tar in another directory, unpacking with the -p option to preserve ownership.

These examples ... from our Linux Basics and Linux Admin courses - run yesterday and today, and next running early next month ...
[trainee@easterton ~]$
(written 2008-11-18)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
A162 - Web Application Deployment - Backups and File System Management
  [153] Linux - where to put swap space - (2004-12-16)
  [334] Symbolic links and hard links - (2005-06-02)
  [554] What backup is adequate? - (2006-01-04)
  [593] Finding where the disc space has gone - (2006-02-06)
  [703] Copying files and preserving ownership - (2006-04-28)
  [735] Boys will be boys, saved by Ubuntu - (2006-05-27)
  [754] tar, jar, war, ear, sar files - (2006-06-10)
  [1013] Copy multiple files - confusing error message from cp - (2006-12-30)
  [1023] Finding public writeable things on your linux file system - (2007-01-06)
  [1288] Linux run states, shell special commands, and directory structures - (2007-08-03)
  [1439] Linux / Unix - layout of operating system files - (2007-11-20)
  [1648] The tourists guide to Linux - (2008-05-20)
  [1765] Dialects of English and Unix - (2008-08-21)
  [1801] Will your backups work if you have to restore them? - (2008-09-18)
  [2299] How much space does my directory take - Linux - (2009-07-20)
  [4056] An overpractical test of our backup strategy! - (2013-03-30)
  [4063] Backups by crossover between network centres - setting up automatic scp transfers - (2013-04-13)
  [4115] More or less back - what happened to our server the other day - (2013-06-14)
  [4390] Checking MySQL database backups have worked (not failed) - (2015-01-10)
  [4400] Commenting out an echo killed my bash backup script - (2015-01-19)
  [4405] Backup procedures - via backup server - (2015-01-24)
  [4481] Extracting data from backups to restore selected rows from MySQL tables - (2015-05-01)

A101 - Web Application Deployment - Linux -An Introduction For Users
  [73] vi - full circle - (2004-10-04)
  [74] pushd and popd - (2004-10-05)
  [152] Aladdin, or careful what you wish. - (2004-12-15)
  [249] An easy way out - (2005-03-17)
  [430] Linux commands - some basics - (2005-08-31)
  [431] File permissions of Linux and Unix systems - (2005-08-31)
  [659] Web Application Components - (2006-03-28)
  [679] More or less on the edge of the page - (2006-04-11)
  [710] Linux training Glasgow, Python programming course Dundee - (2006-05-05)
  [711] THE home directory or MY home directory - (2006-05-06)
  [749] Cottage industry or production line data handling methods - (2006-06-07)
  [984] Cardinal numbers and magic numbers - (2006-12-14)
  [1012] Moving files between Windows / DOS and Linux / Unix - (2006-12-30)
  [1068] ls -l report, Linux / Unix - types and permssions - (2007-02-06)
  [1259] Where am I and how did I get here? - (2007-07-05)
  [1287] Work and play at Well House Manor - Football and Shell Shortcuts - (2007-08-02)
  [1366] awk - a powerful data extraction and manipulation tool - (2007-09-25)
  [1408] Wireless hotel tips - FTP and Skype connections failing - (2007-10-26)
  [1438] Copy and paste / cut and paste and other vi techniques - (2007-11-20)
  [1527] Selecting file names in a shell - one word or another - (2008-02-02)
  [1651] ls command - favourite options - (2008-05-23)
  [1764] Yank and Push - copy and move in vi - (2008-08-21)
  [1803] FTP passive mode - a sometimes cure for upload hangs - (2008-09-20)
  [1897] Keeping on an even keel - (2008-11-21)
  [1902] sstrwxrwxrwx - Unix and Linux file permissions - (2008-11-23)
  [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23)
  [2201] Running straight from the jar, but not from a tar - (2009-05-26)
  [2203] Always use su with minus. And where do programs come from? - (2009-05-27)
  [2300] What does x on a linux directory mean? - (2009-07-21)
  [2479] Accidentally typed ci rather than vi? - (2009-10-27)
  [2494] Making Linux Politically correct - (2009-11-06)
  [2636] Linux - useful tips including history and file name completion - (2010-02-15)
  [2831] Recording (a macro) in vi - (2010-06-27)
  [3179] Oops - I typed ci not vi, and have lost my file ... - (2011-02-21)
  [3256] Displaying a directory or file system tree - Linux - (2011-04-22)
  [3791] The Kernel, Shells and Daemons. Greek Gods in computing - (2012-07-01)
  [3819] Packing a tar, jar or war file - best practise - (2012-07-26)


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Shopping in Melksham
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MySQL database from Ruby - an example
Ruby mixins, modules, require and include
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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