m4: Shell commands

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1 13 Macros for running shell commands
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1 There are a few builtin macros in 'm4' that allow you to run shell
1 commands from within 'm4'.
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1    Note that the definition of a valid shell command is system
1 dependent.  On UNIX systems, this is the typical '/bin/sh'.  But on
1 other systems, such as native Windows, the shell has a different syntax
1 of commands that it understands.  Some examples in this chapter assume
1 '/bin/sh', and also demonstrate how to quit early with a known exit
1 value if this is not the case.
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Menu

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· Platform macros             Determining the platform
· Syscmd                      Executing simple commands
· Esyscmd                     Reading the output of commands
· Sysval                      Exit status
· Mkstemp                     Making temporary files
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