脚本编程之函数:
function:功能
结构化编程,不能独立运行,需要调用时执行,可以被多次调用
定义一个函数(下面两种用法等效)
function FUNCTION {
command
}
FUNCNAME() {
command
}
例子:
#!/bin/bash
function SHOWMENU {
#SHOWMENU() {
cat << EOF
d|D) show disk usages
m|M) show memory usages
s|S) show swap usages
q|Q) quit.
EOF
}
SHOWMENU
read -p “Your choice:” CHOICE
until [ $CHOICE == ‘q’ -o $CHOICE == ‘Q’ ]; do
case $CHOICE in
d|D) df -lh ;;
m|M) free -m | grep “^Mem” ;;
s|S) free -m | grep “^Swap” ;;
*)
SHOWMENU
read -p "Your choice,again: " CHOICE ;;
esac
SHOWMENU
read -p "Your choice: " CHOICE
done
自定义执行状态返回值:
return #
0-255
例子:
#!/bin/bash
ADDUSER() {
USERNAME=hadoop
if ! id -u $USERNAME &> /dev/null; then
useradd $USERNAME
echo $USERNAME | passwd --stdin $USERNAME &&