在Bash中解析命令行参数的最佳方法? [英] Best way to parse command line args in Bash?
问题描述
经过几天的研究，我仍然不知道在其中解析cmdline args的最佳方法.sh脚本.根据我的参考资料，getopts cmd是可行的方法，因为它"在不干扰位置参数变量的情况下提取并检查开关.意外开关或缺少参数的开关会被识别并报告为错误."
After several days of research, I still can't figure out the best method for parsing cmdline args in a .sh script. According to my references the getopts cmd is the way to go since it "extracts and checks switches without disturbing the positional parameter variables.Unexpected switches, or switches that are missing arguments, are recognized and reportedas errors."
当涉及空格时，位置参数(例如2-$ @，$#等)显然不能很好地工作，但可以识别常规参数和长参数(-p和--longparam).我注意到，当传递带有嵌套引号的参数时，这两种方法均会失败(这是引号"的示例.".).这三个代码示例中的哪一个最能说明如何处理cmdline args?专家们不推荐 getopt 功能，因此我正在尝试避免使用该功能！
Positional params(Ex. 2 - $@, $#, etc) apparently don't work well when spaces are involved but can recognize regular and long parameters(-p and --longparam). I noticed that both methods fail when passing parameters with nested quotes ("this is an Ex. of ""quotes""."). Which one of these three code samples best illustrates the way to deal with cmdline args? The getopt function is not recommended by gurus, so I'm trying to avoid it!
示例1:
#!/bin/bash
for i in "$@"
do
case $i in
-p=*|--prefix=*)
PREFIX=`echo $i | sed 's/[-a-zA-Z0-9]*=//'`
;;
-s=*|--searchpath=*)
SEARCHPATH=`echo $i | sed 's/[-a-zA-Z0-9]*=//'`
;;
-l=*|--lib=*)
DIR=`echo $i | sed 's/[-a-zA-Z0-9]*=//'`
;;
--default)
DEFAULT=YES
;;
*)
# unknown option
;;
esac
done
exit 0
示例2:
#!/bin/bash
echo ‘number of arguments’
echo "\$#: $#"
echo "
echo ‘using $num’
echo "\$0: $0"
if [ $# -ge 1 ];then echo "\$1: $1"; fi
if [ $# -ge 2 ];then echo "\$2: $2"; fi
if [ $# -ge 3 ];then echo "\$3: $3"; fi
if [ $# -ge 4 ];then echo "\$4: $4"; fi
if [ $# -ge 5 ];then echo "\$5: $5"; fi
echo "
echo ‘using $@’
let i=1
for x in $@; do
echo "$i: $x"
let i=$i+1
done
echo "
echo ‘using $*’
let i=1
for x in $*; do
echo "$i: $x"
let i=$i+1
done
echo "
let i=1
echo ‘using shift’
while [ $# -gt 0 ]
do
echo "$i: $1"
let i=$i+1
shift
done
[/bash]
output:
bash> commandLineArguments.bash
number of arguments
$#: 0
using $num
$0: ./commandLineArguments.bash
using $@
using $*
using shift
#bash> commandLineArguments.bash "abc def" g h i j*
示例3:
#!/bin/bash
while getopts ":a:" opt; do
case $opt in
a)
echo "-a was triggered, Parameter: $OPTARG" >&2
;;
\?)
echo "Invalid option: -$OPTARG" >&2
exit 1
;;
:)
echo "Option -$OPTARG requires an argument." >&2
exit 1
;;
esac
done
exit 0
推荐答案
我发现使用getopt最简单.它提供对参数的正确处理，否则将很棘手.例如，getopt将知道如何处理在命令行上指定为--arg=option或--arg option的long选项的参数.
I find the use of getopt to be the easiest. It provides correct handling of arguments which is tricky otherwise. For example, getopt will know how to handle arguments to a long option specified on the command line as --arg=option or --arg option.
在解析传递给shell脚本的任何输入时，有用的是使用"$@"变量.请参见bash手册页，以了解与$@的不同之处.这样可以确保您可以处理包含空格的参数.
What is useful in parsing any input passed to a shell script is the use of the "$@" variables. See the bash man page for how this differs from $@. It ensures that you can process arguments that include spaces.
这是一个示例，说明如何编写脚本来解析一些简单的命令行参数:
Here's an example of how I might write s script to parse some simple command line arguments:
#!/bin/bash
args=$(getopt -l "searchpath:" -o "s:h" -- "$@")
eval set -- "$args"
while [ $# -ge 1 ]; do
case "$1" in
--)
# No more options left.
shift
break
;;
-s|--searchpath)
searchpath="$2"
shift
;;
-h)
echo "Display some help"
exit 0
;;
esac
shift
done
echo "searchpath: $searchpath"
echo "remaining args: $*"
并以此表示保留空格和引号:
And used like this to show that spaces and quotes are preserved:
user@machine:~/bin$ ./getopt_test --searchpath "File with spaces and \"quotes\"."
searchpath: File with spaces and "quotes".
remaining args: other args
可以在此处找到有关使用getopt的一些基本信息.
Some basic information about the use of getopt can be found here
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