Shell Scripts相关

• 获得变量长度
  length = ${#var}
  
• 识别root用户
  #!/bin/bash
  if [ $UID -ne 0 ]; then
  echo "I'm not root"
  else
  echo "I'm root!"
  fi
  
• 数学运算
  

#!/bin/bash
n1=4;
n2=5;
let result=n1+n2
echo $result
let不支持小数
bc用于数学计算的高级工具。
echo "sqrt(1.44)" | bc
echo "10^2" | bc
[email protected]:~/shellscripts$ echo "sqrt(1.44)" | bc
1.20
[email protected]:~/shellscripts$ echo "10^2" | bc
100
[email protected]:~/shellscripts$ echo "10^4" | bc
10000