参考：https://www.computerhope.com/unix/bash/getopts.htm
如果使用shell指定参数名称传参，是使用到了“getopts”命令，下面举个例子，定义入参（-n NAME and -t TIMES.）并获取参数，里面已包含注释：
#!/bin/bash # 1. 定义参数变量名 NAME="" # Name of person to greet. TIMES=1 # Number of greetings to give. # 2. 用法提示 usage() { # Function: Print a help message. echo "Usage: $0 [ -n NAME ] [ -t TIMES ]" 1>&2 } exit_abnormal() { # Function: Exit with error. usage exit 1 } # 3. while循环设置进定义的变量名，并校验参数的合法性 while getopts ":n:t:" options; do # Loop: Get the next option; # use silent error checking; # options n and t take arguments. case "${options}" in # n) # If the option is n, NAME=${OPTARG} # set $NAME to specified value. ;; t) # If the option is t, TIMES=${OPTARG} # Set $TIMES to specified value. re_isanum='^[0-9]+$' # Regex: match whole numbers only if ! [[ $TIMES =~ $re_isanum ]] ; then # if $TIMES not whole: echo "Error: TIMES must be a positive, whole number." exit_abnormal exit 1 elif [ $TIMES -eq "0" ]; then # If it's zero: echo "Error: TIMES must be greater than zero." exit_abnormal # Exit abnormally. fi ;; :) # If expected argument omitted: echo "Error: -${OPTARG} requires an argument." exit_abnormal # Exit abnormally. ;; *) # If unknown (any other) option: exit_abnormal # Exit abnormally. ;; esac done # 4. 使用定义的变量名 if [ "$NAME" = "" ]; then # If $NAME is an empty string, STRING="Hi!" # our greeting is just "Hi!" else # Otherwise, STRING="Hi, $NAME!" # it is "Hi, (name)!" fi COUNT=1 # A counter. while [ $COUNT -le $TIMES ]; do # While counter is less than # or equal to $TIMES, echo $STRING # print a greeting, let COUNT+=1 # then increment the counter. done exit 0
运行结果：
./greeting Hi! ----- ./greeting -n Dave Hi, Dave! ----- ./greeting -t 3 Hi! Hi! Hi! ----- ./greeting -t 4 -n Betty Hi, Betty! Hi, Betty! Hi, Betty! Hi, Betty! ------ ./greeting -n Error: -n requires an argument. Usage: ./greeting [ -n NAME ] [ -t TIMES ] ------ ./greeting -t Error: -t requires an argument. Usage: ./greeting [ -n NAME ] [ -t TIMES ] ------ ./greeting -t 0 Error: TIMES must be greater than zero. Usage: ./greeting [ -n NAME ] [ -t TIMES ]
