bash ksh 变量接受的最大字符数是多少？
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What is the maximum number of characters that the ksh variable accepts?
提问by javapadawan
I am trying to load and parse a really large text file. Although the loading is not a problem, but there are particular lines that have 2908778 characters on a single line.
我正在尝试加载和解析一个非常大的文本文件。虽然加载没有问题，但是有一些特定的行单行有 2908778 个字符。
This is causing an error in my script.
这导致我的脚本出错。
On the script below, I removed all logic and just got straight to read line. I also removed all valid lines and just left the really long line in one text file. When running I get the below error :
在下面的脚本中，我删除了所有逻辑并直接阅读了一行。我还删除了所有有效的行，只在一个文本文件中留下了很长的一行。运行时出现以下错误：
$ dowhiledebug.sh dump.txt
dowhiledebug.sh[6]: no space
Script Ended dump.txt
The actual script:
实际脚本：
#!/bin/sh
filename=
count=1
if [ -f ${filename} ]; then
echo "after then"
while read line;
do
echo "$count"
count=$((count+1))
done < $filename
else
echo "Could not open file $filename"
fi
echo "Script Ended $filename"
Updated (2013-01-17)
更新 (2013-01-17)
Follow up question : Is it possible to increase the maximum number of characters that ksh variable accepts?
采纳答案by David W.
The limit for any shell is the limit of the C command line maximum. Here's a little program that pulls the information out of /usr/include/limits.hfor you:
任何 shell 的限制都是 C 命令行最大值的限制。这是一个小程序，可以/usr/include/limits.h为您提取信息：
cpp <<HERE | tail -1
#include <limits.h>
ARG_MAX
HERE
Mine gives me (256 * 1024) or 262144 characters.
我的给了我 (256 * 1024) 或 262144 个字符。
Doesn't work if the C compiler isn't installed, but it's probably a similar limit.
如果未安装 C 编译器，则不起作用，但这可能是类似的限制。
回答by shellter
what OS and version of ksh? Can you echo ${.sh.version}and get a value? If so, please include in your question above. Or could this be pdksh?
什么操作系统和版本的ksh？你能echo ${.sh.version}得到一个值吗？如果是这样，请包括在您上面的问题中。或者这可能是 pdksh？
Here's a test that will get you in the ballpark, assuming a modern ksh supporting (( i++ ))math evaluations:
假设现代 ksh 支持(( i++ ))数学评估，这里有一个测试可以让您进入球场：
#100 char var
var=1234578901234456789012345678901234567890123456789012345789012344567890123456789012345678901234567890
$ while (( i++ < 10000 )) ;do var="$var$var" ; print "i=$i\t" ${#var} ; done
i=1 200
i=2 400
i=3 800
i=4 1600
i=5 3200
i=6 6400
i=7 12800
i=8 25600
i=9 51200
i=10 102400
i=11 204800
i=12 409600
i=13 819200
i=14 1638400
i=15 3276800
i=16 6553600
i=17 13107200
i=18 26214400
i=19 52428800
i=20 104857600
i=21 209715200
i=22 419430400
-ksh: out of memory
$ print -- ${.sh.version}
Version JM 93t+ 2010-05-24
AND that is just the overall size of the environment that can be supported. When dealing with the command-line environment and "words" after the program name, there is a limit to the number of words, regardless of overall size.
而且这只是可以支持的环境的整体大小。在处理命令行环境和程序名后的“单词”时，无论整体大小如何，单词的数量都有限制。
Some shells man page will have a section LIMITS that may show something like max-bytes 200MB, max-args 2048. This information may be in a different section, it will definitely have different labels and different values I have included, OR it may not be there at all, hence the above code loop, so look carefully around and if you find a source for this info, either add an answer to this Q, or update this one.
某些 shell 手册页会有一个 LIMITS 部分，可能会显示类似max-bytes 200MB, max-args 2048. 此信息可能位于不同的部分，它肯定会有不同的标签和我包含的不同值，或者它可能根本不存在，因此上面的代码循环，因此请仔细查看，如果您找到此信息的来源，要么为这个问题添加一个答案，要么更新这个问题。
The bash 4.4std man page doesn't seem to have this information and its harder to find a kshdoc all the time. Check your man kshand hope that you can find a documented limit.
该bash 4.4STD手册页似乎不具备此信息及其很难找到一个ksh文档的所有时间。检查您的man ksh并希望您能找到记录在案的限制。
IHTH
IHTH
