一行中的两个命令
Two commands in one line
为什么会这样：
free | cut -c67- && free | cut -c55-61
给我缓冲区和缓存大小，但是
free -s4 | cut -c67- && free -s4 | cut -c55-61
只给我缓存大小。
来自 Bash 手册页：
SHELL GRAMMA
[...]
Lists
AND and OR lists are sequences of one of more pipelines separated by the && and || control operators, respec‐
tively. AND and OR lists are executed with left associativity. An AND list has the form
command1 && command2
command2 is executed if, and only if, command1 returns an exit status of zero.
在 command1 以 return 值 0 退出之前，&& 运算符不会执行 command2。
命令 free -s4 | cut -c67-,56-61 是否更接近您想要的？
为什么会这样：
free | cut -c67- && free | cut -c55-61
给我缓冲区和缓存大小，但是
free -s4 | cut -c67- && free -s4 | cut -c55-61
只给我缓存大小。
来自 Bash 手册页：
SHELL GRAMMA [...] Lists AND and OR lists are sequences of one of more pipelines separated by the && and || control operators, respec‐ tively. AND and OR lists are executed with left associativity. An AND list has the form command1 && command2 command2 is executed if, and only if, command1 returns an exit status of zero.
在 command1 以 return 值 0 退出之前，&& 运算符不会执行 command2。
命令 free -s4 | cut -c67-,56-61 是否更接近您想要的？