我一直在学习命令行参数解析。关于这件事已经有很多线索了，我不是要在这里挑起一个：
Using getopts in bash shell script to get long and short command line options
How do I parse command line arguments in Bash?
使用getopts，如果您想解析像“-opt value”这样的参数/值对，一种方法是让getopts将其视为名为“-”的参数，并且值变为“-opt”。然后我们解析它并通过符号${!OPTIND}获取用户值。我需要知道更多。
在我上面引用的第一个线程中，${!OPTIND}被使用，有人说“那是什么？”答案是“这是一种间接的替代”。在阅读了关于间接引用的注释，特别是https://unix.stackexchange.com/questions/41292/variable-substitution-with-an-exclamation-mark-in-bash和http://mywiki.wooledge.org/BashFAQ/006之后，我通常理解间接引用，但是我不理解${!OPTIND}作为间接引用的例子。$OPTIND的值是一个整数，是下一个命令行参数的索引。它不是另一个数组中的值。
在上面的bashfaq/006链接中，有关于间接寻址的警告和不使用它的一般建议。也许没什么大不了的，但我想尽量避免危险。
我们能避免间接的攻击吗？似乎我应该可以使用${OPTIND}作为一个整数，从$@，$@[$OPTIND]}中获取一个值。
如果需要示例，这里有一个名为“cli-6.sh”的脚本，它将接收不带等号的长格式参数。像这样跑：
$ ./cli-6.sh -v --fred good --barney bad --wilma happy
不要使用-v来减少冗长。
$ ./cli-6.sh --fred good --barney bad --wilma happy
After Parsing values, ordinary getopts
VERBOSE 0
Arrays of opts and values
optary: fred barney wilma
valary: good bad happy
希望，这也适用于您：）我没有使用关联数组来保存值，因为我希望这最终可以在其他shell中工作。
#/usr/bin/env bash
die() {
printf '%s\n' "$1" >&2
exit 1
}
printparse(){
if [ ${VERBOSE} -gt 0 ]; then
printf 'Parse: %s%s%s\n' "$1" "$2" "$3" >&2;
fi
}
showme(){
if [ ${VERBOSE} -gt 0 ]; then
printf 'VERBOSE: %s\n' "$1" >&2;
fi
}
VERBOSE=0
## index for imported values in optary and valary arrays
idx=0
## Need v first so VERBOSE is set early
optspec=":vh-:"
while getopts "$optspec" OPTCHAR; do
case "${OPTCHAR}" in
-)
showme "OPTARG: ${OPTARG[*]}"
showme "OPTIND: ${OPTIND[*]}"
showme "OPTCHAR: ${OPTCHAR}"
showme "There is no equal sign in ${OPTARG}"
opt=${OPTARG}
val="${!OPTIND}"; OPTIND=$(( $OPTIND + 1 ))
printparse "--${OPTARG}" " " "\"${val}\""
if [[ "$val" == -* ]]; then
die "ERROR: $opt value must be supplied"
fi
optary[${idx}]=${opt}
valary[${idx}]=${val}
idx=$(($idx + 1))
;;
h)
echo "usage: $0 [-v] [--anyOptYouQant[=]<valueIsRequired>] [--another[=]<value>]" >&2
exit 2
;;
v)
## if -v flag is present, it means TRUE
VERBOSE=1
;;
*)
if [ "$OPTERR" != 1 ] || [ "${optspec:0:1}" = ":" ]; then
die "Undefined argument: '-${OPTARG}'"
fi
;;
esac
done
echo "After Parsing values, ordinary getopts"
echo "VERBOSE $VERBOSE"
echo 'Arrays of opts and values'
echo "optary: ${optary[*]}"
echo "valary: ${valary[*]}"
最佳答案
不确定这是否有用，但这里是cli options解析器的bash-only版本，它不使用getopts，但接受短参数和长参数。它还处理短格式参数组。这在不支持最新版本getopts的系统上应该很有用。
#!/bin/bash
#
# Copyright (c) 2017 by Joe Linoff
# MIT Open Source License.
#
# This script shows how to implement an argument parser with
# 4 options. Two of the options are simply flags, one of
# of them has a single argument and the other has 2 arguments.
#
# It is meant to show bash can support reasonably complex
# argument parsing idioms that will make shell scripts
# more user friendly without using getopts. It is useful
# for cases where getopts is not available.
#
# The options demonstrated are:
#
# 1. -h or --help
# 2. -v or --verbose
# 3. -f ARG or --file ARG or --file=ARG
# 4. -c ARG1 ARG2 or --compare ARG1 ARG2
#
# The options parsing allows the following specifications.
#
# 1. -h
# 2. --help
# 3. -v
# 4. --verbose
# 5. -vv
# 6. -f ARG1
# 7. --file ARG1
# 8. --file=ARG1
# 9. -c ARG1 ARG2
# 10. --compare ARG1 ARG2
#
# This example does not show how to implement best match which would
# mean accepting an option like "--com" (because it is the best unique
# match to --compare). That could be added but i am not convinced
# that it is worth the overhead.
#
# The options parser is global in this example because it is setting
# global (script wide) variables.
# ========================================================================
# Functions
# ========================================================================
# Simple error function that prints the line number of the caller and
# highlights the message in red.
function _err() {
echo -e "\033[31;1mERROR:\033[0;31m:${BASH_LINENO[0]} $*\033[0m"
exit 1
}
# ========================================================================
# Main
# ========================================================================
CARGS=()
FILE=''
HELP=0
VERBOSE=0
# The OPT_CACHE is to cache short form options.
OPT_CACHE=()
while (( $# )) || (( ${#OPT_CACHE[@]} )) ; do
if (( ${#OPT_CACHE[@]} > 0 )) ; then
OPT="${OPT_CACHE[0]}"
if (( ${#OPT_CACHE[@]} > 1 )) ; then
OPT_CACHE=(${OPT_CACHE[@]:1})
else
OPT_CACHE=()
fi
else
OPT="$1"
shift
fi
case "$OPT" in
# Handle the case of multiple short arguments in a single
# string:
# -abc ==> -a -b -c
-[!-][a-zA-Z0-9\-_]*)
for (( i=1; i<${#OPT}; i++ )) ; do
# Note that the leading dash is added here.
CHAR=${OPT:$i:1}
OPT_CACHE+=("-$CHAR")
done
;;
-h|--help)
(( HELP++ ))
;;
-v|--verbose)
# Increase the verbosity.
# Can accept: -v -v OR -vv.
(( VERBOSE++ ))
;;
-f|--file|--file=*)
# Can be specified multiple times but we only accept the
# last one.
# Can accept: --file foo and --file=foo
if [ -z "${OPT##*=*}" ] ; then
FILE="${OPT#*=}"
else
FILE="$1"
shift
fi
[[ -z "$FILE" ]] && _err "Missing argument for '$OPT'."
;;
-c|--compare)
# Can be specified multiple times but we only accept the
# last one.
# Can accept:
# --compare ARG1 ARG2
# Cannot accept:
# --compare=*
# The reason for not accepting the '=' sign is to reduce
# complexity because of the ambiguity of separators. If
# you decide that you will always use a comma as the
# separator, that is fine until one of the arguments
# contains a comma.
CARG1="$1"
CARG2="$2"
shift 2
[[ -z "$CARG1" ]] && _err "Missing both arguments for '$OPT'."
[[ -z "$CARG2" ]] && _err "Missing second argument for '$OPT'."
CARGS=()
CARGS+=("$CARG1")
CARGS+=("$CARG2")
;;
-*)
_err "Unrecognized option '$OPT'."
;;
*)
_err "Unrecognized argument '$OPT'."
;;
esac
done
echo "COMPARE : ${CARGS[@]}"
echo "FILE : ${FILE}"
echo "HELP : ${HELP}"
echo "VERBOSE : ${VERBOSE}"
代码也可以从https://gist.github.com/jlinoff/1876972c0b37259c82367d51c8313171获得。
关于linux - 在getopts中说明$ {!OPTIND}。有危险吗备择方案？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/46813395/