bash 如何在 POSIX sh 中标记数组？
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How to mark an array in POSIX sh?
提问by Charles
While replacing external commands in a shell script, I used an array to get rid of awk's NF.
在 shell 脚本中替换外部命令时，我使用了一个数组来摆脱 awk 的NF.
Now, since I moved from bash to POSIX sh, I cannot get the array marked right:
现在，由于我从 bash 转移到 POSIX sh，我无法正确标记数组：
#!/bin/bash
export RANGE="0 1 4 6 8 16 24 46 53"
RANGE=($RANGE)
echo arrayelements: $((${#RANGE[@]}))
LAST=$((${#RANGE[@]}-1))
echo "Last element(replace NF): ${RANGE[$LAST]}"
# ./foo
arrayelements: 9
Last element(replace NF): 53
I'm using OpenBSD's, sh and it has exactly the same size as the ksh.
Changing above to /bin/sh, it seems that the following doesn't work:
我正在使用 OpenBSD 的 sh，它的大小与 ksh 完全相同。将上面更改为/bin/sh，以下似乎不起作用：
set -A "$RANGE"
set -- "$RANGE"
How could I realise the above script in /bin/sh? (Note that it works fine if you invoke bash with --posix, that's not what I look for.)
我怎么能在/bin/sh. （请注意，如果您使用 bash 调用它可以正常工作--posix，这不是我要找的。）
回答by Matthew Slattery
Arrays are not part of the POSIX shspecification.
数组不是POSIXsh规范的一部分。
There are various other ways to find the last item. A couple of possibilities:
有多种其他方法可以找到最后一个项目。几种可能性：
#!/bin/sh
export RANGE="0 1 4 6 8 16 24 46 53"
for LAST_ITEM in $RANGE; do true; done
echo "Last element(replace NF): $LAST_ITEM"
or:
或者：
#!/bin/sh
export RANGE="0 1 4 6 8 16 24 46 53"
LAST_ITEM="${RANGE##* }"
echo "Last element(replace NF): $LAST_ITEM"
回答by Sammy S.
You can use the following project from Github, which implements a POSIX-compliant array, which works in all shells I tried: https://github.com/makefu/array
您可以使用 Github 中的以下项目，该项目实现了符合 POSIX 标准的数组，该数组适用于我尝试过的所有 shell：https: //github.com/makefu/array
It is not very convenient to use, but I found it to work well for my purposes.
使用起来不是很方便，但我发现它很适合我的目的。
回答by ralph
The following code works for me using the Heirloom Bourne Shell:
以下代码适用于使用Heirloom Bourne Shell 的我：
#!/usr/local/bin/bournesh
# cf. Heirloom Bourne Shell,
# http://freshmeat.net/projects/bournesh/
# http://www.in-ulm.de/~mascheck/bourne/
# use a caret as a pipe symbol to make sure it's a Bourne shell
# cf. http://mywiki.wooledge.org/BourneShell
ls ^ cat 1>/dev/null 2>&1 ||
{ echo 'No true Bourne shell! ... exiting ...'; exit 1; }
IFS=' '
unset RANGE
RANGE="0 1 4 6 8 16 24 46 53"
export IFS RANGE
set -- $RANGE
echo arrayelements: $#
LAST=$#
eval echo "Last element\(replace NF\): $$#"
Note that IFSis set to a space and there are no double quotes around $RANGE.
请注意，IFS设置为空格并且 周围没有双引号$RANGE。
