grep-e

grep -q用于if逻辑判断

突然发现grep -q 用于if 逻辑判断很好用。

-q 参数，本意是 Quiet; do not write anything to standard output. Exit immediately with zero status if any match is found, even if an error was detected. 中文意思为，安静模式，不打印任何标准输出。如果有匹配的内容则立即返回状态值0。

小应用

cat a.txt
nihao
nihaooo
hello

if grep -q hello a.txt ; then echo yes;else echo no; fi
yes
if grep -q word a.txt; then echo yes; else echo no; fi
no