用于自动执行并行grep的简单Makefile返回错误

我经常使用Makefiles来自动执行重复执行的任务。例如，一项任务涉及搜索不断增长的数据集以查找正则表达式匹配项。假设我有以下两个文本文件，

search1.txt

，和

search2.txt

：

DSADJKBSDJSA
TEST1
DJKSABVDJSA

hvdsjhavdjshavdsa
dsadsadsadsa
TEST3djsabdjhsavdjhsa
TEST2dsajdbsahjdvsa

search1.txt

：

DSADJKBSDJSA
TEST1
DJKSABVDJSA

hvdsjhavdjshavdsa
dsadsadsadsa
TEST3djsabdjhsavdjhsa
TEST2dsajdbsahjdvsa

search2.txt

：

DSADJKBSDJSA
TEST1
DJKSABVDJSA

hvdsjhavdjshavdsa
dsadsadsadsa
TEST3djsabdjhsavdjhsa
TEST2dsajdbsahjdvsa

下面是我的Makefile，它使用gnupallel并行搜索这些文件

.PHONY: search
search:
    find search*.txt | parallel grep TEST1 {}
    find search*.txt | parallel grep TEST2 {}

当我运行

makesearch

时，第一行输出正确的数据，然后抛出一个错误并退出，尽管单独运行这两行可以很好地完成

> make search
find *.txt | parallel grep TEST1 {}
TEST1
make: *** [search] Error 1
> find *.txt | parallel grep TEST1 {}
TEST1
> find *.txt | parallel grep TEST2 {}
TEST2dsajdbsahjdvsa
> parallel --version
GNU parallel 20160822

---

我一辈子都搞不清楚我做错了什么。这肯定是显而易见的，但我已经将其浓缩到一个如此简单的小例子中，我仍然不明白为什么会发生这种情况。谢谢你对我的帮助

啊哈！我想出来了。结果表明，grep的退出状态导致了这种情况。从grep手册页：

EXIT STATUS
     The grep utility exits with one of the following values:

     0     One or more lines were selected.
     1     No lines were selected.
     >1    An error occurred.

由于我正在搜索的某些文件不包含匹配项，grep将返回退出状态1。这有一个非常简单的修复方法：

.PHONY: search
search:
    find search*.txt | parallel grep TEST1 {} || true
    find search*.txt | parallel grep TEST2 {} || true