$( CMD ) 将会执行 CMD, 然后用 CMD 的输出作为整体的值. 例如:
for file in $(ls)
会遍历当前目录的文件
[[]] 进行比较:
if [[ $? -ne 0 ]]; thenecho "File $file does not have any foobar, adding one"echo "# foobar" >> "$file"
fi
通配符:
? 匹配任意一个字符
* 匹配任意个字符
{} 可以自动展开, 比如:
convert image.{png,jpg}
# will expand to
convert image.png image.jpg
# Show differences between files in foo and bar
diff <(ls foo) <(ls bar)
