1*b0c40a00SSimon J. Gerraty# $NetBSD: varmod-shell.mk,v 1.6 2021/02/14 20:16:17 rillig Exp $ 22c3632d1SSimon J. Gerraty# 3*b0c40a00SSimon J. Gerraty# Tests for the ':!cmd!' variable modifier, which runs the shell command 4*b0c40a00SSimon J. Gerraty# given by the variable modifier and returns its output. 5e2eeea75SSimon J. Gerraty# 6e2eeea75SSimon J. Gerraty# This modifier has been added on 2000-04-29. 7e2eeea75SSimon J. Gerraty# 8e2eeea75SSimon J. Gerraty# See also: 9e2eeea75SSimon J. Gerraty# ApplyModifier_ShellCommand 102c3632d1SSimon J. Gerraty 11e2eeea75SSimon J. Gerraty# The command to be run is enclosed between exclamation marks. 12e2eeea75SSimon J. Gerraty# The previous value of the expression is irrelevant for this modifier. 13e2eeea75SSimon J. Gerraty# The :!cmd! modifier turns an undefined expression into a defined one. 14e2eeea75SSimon J. Gerraty.if ${:!echo word!} != "word" 15e2eeea75SSimon J. Gerraty. error 16e2eeea75SSimon J. Gerraty.endif 17e2eeea75SSimon J. Gerraty 18e2eeea75SSimon J. Gerraty# If the command exits with non-zero, an error message is printed. 19e2eeea75SSimon J. Gerraty# XXX: Processing continues as usual though. 20e2eeea75SSimon J. Gerraty# 21e2eeea75SSimon J. Gerraty# Between 2000-04-29 and 2020-11-17, the error message mentioned the previous 22e2eeea75SSimon J. Gerraty# value of the expression (which is usually an empty string) instead of the 23e2eeea75SSimon J. Gerraty# command that was executed. It's strange that such a simple bug could 24e2eeea75SSimon J. Gerraty# survive such a long time. 25e2eeea75SSimon J. Gerraty.if ${:!echo word; false!} != "word" 26e2eeea75SSimon J. Gerraty. error 27e2eeea75SSimon J. Gerraty.endif 28e2eeea75SSimon J. Gerraty.if ${:Uprevious value:!echo word; false!} != "word" 29e2eeea75SSimon J. Gerraty. error 30e2eeea75SSimon J. Gerraty.endif 31e2eeea75SSimon J. Gerraty 322c3632d1SSimon J. Gerratyall: 33