Makefile - some basics, and a demonstration

For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))

Here is a basic rule from a makefile:

  mytarget:   mysource

      echo "myactions"

      uptime > mytarget

      cat -n mysource >> mytarget

mytarget depends on mysource. In other words, the following commands, which are the "rule" that's used to make mytarget from mysource are run if
1. mytarget does not exist or
2. mysource has a more recent timestamp than mytarget, indication that mytarget is out of date.

It is CRITICALLY IMPORTANT that each rule line is preceeded by tabs and not space.

I've created a file called mysource, but no file called mytarget. Let's see how that works:

wizard:mc graham$ ls -l my*

-rw-r--r--  1 graham  staff  45 13 Mar 13:06 mysource

wizard:mc graham$ make

echo "myactions"

myactions

uptime > mytarget

cat -n mysource >> mytarget

The actions (a.k.a. rules, a.k.a. script) have been run and mytarget created:

wizard:mc graham$ ls -l my*

-rw-r--r--  1 graham  staff   45 13 Mar 13:06 mysource

-rw-r--r--  1 graham  staff  122 13 Mar 13:20 mytarget

I run the make again, but there's nothing to be done as mytarget is up to date:

wizard:mc graham$ make

make: `mytarget' is up to date.

wizard:mc graham$ ls -l my*

-rw-r--r--  1 graham  staff   45 13 Mar 13:06 mysource

-rw-r--r--  1 graham  staff  122 13 Mar 13:20 mytarget

I modify mysource - the incoming file. That means mytarget is old (out of date) so when I rerun make, mytarget gets rebuilt:

wizard:mc graham$ echo "Hello World again" >> mysource

wizard:mc graham$ ls -l my*

-rw-r--r--  1 graham  staff   63 13 Mar 13:22 mysource

-rw-r--r--  1 graham  staff  122 13 Mar 13:20 mytarget

wizard:mc graham$ make

echo "myactions"

myactions

uptime > mytarget

cat -n mysource >> mytarget

wizard:mc graham$ ls -l my*

-rw-r--r--  1 graham  staff   63 13 Mar 13:22 mysource

-rw-r--r--  1 graham  staff  147 13 Mar 13:22 mytarget

But if I repeat the same make, mytarget is now correctly dated and so there is nothing to do:

wizard:mc graham$ make

make: `mytarget' is up to date.

wizard:mc graham$

(written 2012-03-13, updated 2012-03-14)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles

A168 - Web Application Deployment - Compiler and development tools
  [694] Ant and Make - (2006-04-22)
  [1671] Compiling C programs with gcc - an overview - (2008-06-10)
  [2674] Make and makefiles - a commented example to help you learn - (2010-03-12)
  [3053] Make - automating the commands for building and installing - (2010-11-16)
  [3632] What is Make? - (2012-03-02)
  [3652] A Complete makefile example - (2012-03-14)
  [3658] Using Make for a distribution - (2012-03-17)
  [3666] Makefile variables - defined internally, from the command line and from the environment - (2012-03-22)
  [4013] Web Frameworks - nested templates - (2013-02-22)
  [4585] What is make? What is gcc? - (2015-11-28)

Back to
Possessive Regular Expression Matching - Perl, Objective C and some other languages

Previous and next
or
Horse's mouth home

Forward to
A Complete makefile example

Some other Articles

Sights and scenes - more London trip pictures
On a sunny afternoon in London
What is happening in 59 days time in Melksham?
Makefile - some basics, and a demonstration
Possessive Regular Expression Matching - Perl, Objective C and some other languages
A single action for multiple iPad / iPhone buttons, and animation
iPad and iPhone programming - our seminar weekend with Xcode
Along the brook - East Melksham to Melksham
Exploring Melksham with a film maker

4759 posts, page by page

Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page

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.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

Like this? ??