記号

$ sh app.sh argv1 argv2
Option Desc. Example
${$} PID n
${PPID} PPID n
${#} Num of Arg 2
${1} ARG 1 arg1
${@} All ARG argv1 argv2

PID of the most recently executed background command

~  sleep 10 &
echo ${!}
[1] 66889
66889
~  
sleep 10 &
echo ${!}

演算子

比較演算子 意味
-eq a == b
-ge a >= b
-gt a > b
-le a <= b
-lt a < b
-ne a != b