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In m4, how do you include a file with an environment variable in its name?

I want to include a file based on my sandbox base directory inside my m4 text, without using a switch -I.

So far I have figured out how to capture environment variables using a sys call:

define(MODEL_ROOT,`syscmd(`printf $MODEL_ROOT')')dnl

Next, I want to include a file based on this environment variable:

include(MODEL_ROOT/sw/lib/m4_macros/foreach2.m4)

In general, I have:

define(MODEL_ROOT,`syscmd(`printf $MODEL_ROOT')')

MODEL_ROOT

MODEL_ROOT/sw/lib/m4_macros/foreach2.m4

include(MODEL_ROOT/sw/lib/m4_macros/foreach2.m4)

What prints:

/home/ross/sandbox

/home/ross/sandbox/sw/lib/m4_macros/foreach2.m4

/home/ross/sandboxforeach_example.m4:7: m4: Cannot open /sw/lib/m4_macros/foreach2.m4: No such file or directory

I know that for the standard syntax for include there is

include(`file.m4')

But if I quote MODEL_ROOT/sw/lib/m4_macros/foreach2.m4, then m4 is like:

[...]
include(`MODEL_ROOT/sw/lib/m4_macros/foreach2.m4')

m4 complains:

[...]
foreach_example.m4:7: m4: Cannot open MODEL_ROOT/sw/lib/m4_macros/foreach2.m4: No such file or directory

How to include an environment variable file in my path?

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2 answers

I think you need to use esyscmdinstead syscmd. esyscmdreads command line output.

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, GNU esyscmd, . syscmd stdout, divert s.

: MODEL_ROOT : , , m4 .

:

  • include(MODEL_ROOT/sw/lib/m4_macros/foreach2.m4)
  • include(`MODEL_ROOT/sw/lib/m4_macros/foreach2.m4')

:

include(MODEL_ROOT`/sw/lib/m4_macros/foreach2.m4')

MODEL_ROOT, (, , ). "", , , .

, :

define(`HOME', esyscmd(`printf \`\`%s\'\' "$HOME"'))

, , , , . \`\`%s\'\' .

: esyscmd , - . , , , .

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