Makefile If-Then Else and Loops

Question

Can someone explain how to use if-then statements and for loops in Makefiles  I can t seem to find any good documentation with examples

User · Answer

You do see for loops alot of the time  but they are usually not needed  Here is an example of how one might perform a for loop without resorting to the shell  LIST OF THINGS TO DO   do this do that    LIST OF THINGS TO DO           run     gt     out  SUBDIRS   snafu fubar   SUBDIRS        cd     amp  amp    MAKE

User · Answer

Here s an example if   ifeq    strip   OS   Linux          PYTHON    usr bin python         FIND    usr bin find endif   Note that this comes with a word of warning that different versions of Make have slightly different syntax  none of which seems to be documented very well

User · Answer

Have you tried the GNU make documentation  It has a whole section about conditionals with examples

User · Answer

Here s an example if   ifeq    strip   OS   Linux          PYTHON    usr bin python         FIND    usr bin find endif   Note that this comes with a word of warning that different versions of Make have slightly different syntax  none of which seems to be documented very well

User · Answer

Conditional Forms    Simple    conditional-directive text-if-true endif   Moderately Complex    conditional-directive text-if-true else text-if-false endif   More Complex    conditional-directive text-if-one-is-true else conditional-directive text-if-true else text-if-false endif endif   Conditional Directives    If Equal Syntax    ifeq  arg1  arg2  ifeq  arg1   arg2  ifeq  arg1   arg2  ifeq  arg1   arg2  ifeq  arg1   arg2    If Not Equal Syntax    ifneq  arg1  arg2  ifneq  arg1   arg2  ifneq  arg1   arg2  ifneq  arg1   arg2  ifneq  arg1   arg2    If Defined Syntax    ifdef variable-name   If Not Defined Syntax    ifndef variable-name     foreach Function    foreach Function Syntax      foreach var  list  text      foreach Semantics For each whitespace separated word in  list   the variable named by  var  is set to that word and text is executed

User · Answer

Have you tried the GNU make documentation  It has a whole section about conditionals with examples

User · Answer

You do see for loops alot of the time  but they are usually not needed  Here is an example of how one might perform a for loop without resorting to the shell  LIST OF THINGS TO DO   do this do that    LIST OF THINGS TO DO           run     gt     out  SUBDIRS   snafu fubar   SUBDIRS        cd     amp  amp    MAKE

User · Answer

Have you tried the GNU make documentation  It has a whole section about conditionals with examples

User · Answer

Conditional Forms    Simple    conditional-directive text-if-true endif   Moderately Complex    conditional-directive text-if-true else text-if-false endif   More Complex    conditional-directive text-if-one-is-true else conditional-directive text-if-true else text-if-false endif endif   Conditional Directives    If Equal Syntax    ifeq  arg1  arg2  ifeq  arg1   arg2  ifeq  arg1   arg2  ifeq  arg1   arg2  ifeq  arg1   arg2    If Not Equal Syntax    ifneq  arg1  arg2  ifneq  arg1   arg2  ifneq  arg1   arg2  ifneq  arg1   arg2  ifneq  arg1   arg2    If Defined Syntax    ifdef variable-name   If Not Defined Syntax    ifndef variable-name     foreach Function    foreach Function Syntax      foreach var  list  text      foreach Semantics For each whitespace separated word in  list   the variable named by  var  is set to that word and text is executed

User · Answer

Have you tried the GNU make documentation  It has a whole section about conditionals with examples

User · Answer

Here s an example if   ifeq    strip   OS   Linux          PYTHON    usr bin python         FIND    usr bin find endif   Note that this comes with a word of warning that different versions of Make have slightly different syntax  none of which seems to be documented very well

User · Answer

Conditional Forms    Simple    conditional-directive text-if-true endif   Moderately Complex    conditional-directive text-if-true else text-if-false endif   More Complex    conditional-directive text-if-one-is-true else conditional-directive text-if-true else text-if-false endif endif   Conditional Directives    If Equal Syntax    ifeq  arg1  arg2  ifeq  arg1   arg2  ifeq  arg1   arg2  ifeq  arg1   arg2  ifeq  arg1   arg2    If Not Equal Syntax    ifneq  arg1  arg2  ifneq  arg1   arg2  ifneq  arg1   arg2  ifneq  arg1   arg2  ifneq  arg1   arg2    If Defined Syntax    ifdef variable-name   If Not Defined Syntax    ifndef variable-name     foreach Function    foreach Function Syntax      foreach var  list  text      foreach Semantics For each whitespace separated word in  list   the variable named by  var  is set to that word and text is executed

User · Answer

Conditional Forms    Simple    conditional-directive text-if-true endif   Moderately Complex    conditional-directive text-if-true else text-if-false endif   More Complex    conditional-directive text-if-one-is-true else conditional-directive text-if-true else text-if-false endif endif   Conditional Directives    If Equal Syntax    ifeq  arg1  arg2  ifeq  arg1   arg2  ifeq  arg1   arg2  ifeq  arg1   arg2  ifeq  arg1   arg2    If Not Equal Syntax    ifneq  arg1  arg2  ifneq  arg1   arg2  ifneq  arg1   arg2  ifneq  arg1   arg2  ifneq  arg1   arg2    If Defined Syntax    ifdef variable-name   If Not Defined Syntax    ifndef variable-name     foreach Function    foreach Function Syntax      foreach var  list  text      foreach Semantics For each whitespace separated word in  list   the variable named by  var  is set to that word and text is executed

User · Answer

Here s an example if   ifeq    strip   OS   Linux          PYTHON    usr bin python         FIND    usr bin find endif   Note that this comes with a word of warning that different versions of Make have slightly different syntax  none of which seems to be documented very well

[makefile] Makefile If-Then Else and Loops

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