* What does " test ... || gcc ..." mean?
[not found] ` <015701c17e6b$9844f120$7add18ac@amr.corp.intel.com>
@ 2001-12-06 7:57 ` Luker Lu
2001-12-07 4:44 ` Andrea 'Fyre Wyzard' Bocci
0 siblings, 1 reply; 2+ messages in thread
From: Luker Lu @ 2001-12-06 7:57 UTC (permalink / raw)
To: gcc-help
Hi all,
I want to understand the source code of gcc so I am studying the build
process at first. In the process of "make bootstrap", the following command
appears:
test x"no" != xyes || \
gcc -c -DHAVE_CONFIG_H -g -O2 -I. -I../../source/libiberty/../include
../../source/libiberty/argv.c -o pic/argv.o
I know what "test" and "gcc" are, but can't understand the whole command.
Could someone explain me what it does? What does this "||" between test and
gcc mean?
thanks in advance!
Luker Lu
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: What does " test ... || gcc ..." mean?
2001-12-06 7:57 ` What does " test ... || gcc ..." mean? Luker Lu
@ 2001-12-07 4:44 ` Andrea 'Fyre Wyzard' Bocci
0 siblings, 0 replies; 2+ messages in thread
From: Andrea 'Fyre Wyzard' Bocci @ 2001-12-07 4:44 UTC (permalink / raw)
To: Luker Lu, gcc-help
At 16.57 06/12/01 (GMT +0100), Luker Lu wrote:
>Hi all,
>
>I want to understand the source code of gcc so I am studying the build
>process at first. In the process of "make bootstrap", the following command
>appears:
>
>test x"no" != xyes || \
> gcc -c -DHAVE_CONFIG_H -g -O2 -I. -I../../source/libiberty/../include
>../../source/libiberty/argv.c -o pic/argv.o
>
>I know what "test" and "gcc" are, but can't understand the whole command.
>Could someone explain me what it does? What does this "||" between test and
>gcc mean?
>thanks in advance!
>
>Luker Lu
Here is a fast explanation:
|| is the OR operator. It can also be used as a flow control operator, just
like an if-then-else check.
That is, you can write a C style if-then-else block
if (condition)
true-statement
else
false-statement
as
test condition && true-statement || false-statement
However, unlike the C block, the "&& true-statement part" is not necessary,
and can be skipped.
For more infos, have a look at sh or bahs man pages.
fwyzard
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[not found] ` <015701c17e6b$9844f120$7add18ac@amr.corp.intel.com>
2001-12-06 7:57 ` What does " test ... || gcc ..." mean? Luker Lu
2001-12-07 4:44 ` Andrea 'Fyre Wyzard' Bocci
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