如何获取 Bash 版本号
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How to get Bash version number
提问by stwalkerster
I'm writing a script which requires the bash version number in a simple short format.
我正在编写一个脚本，它需要一个简单的短格式的 bash 版本号。
I'm aware of bash --version, but this gives a long output:
我知道bash --version，但这给出了很长的输出：
GNU bash, version 4.2.10(1)-release (i686-pc-linux-gnu)
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
This could be cut down to the bit I want, 4.2.10, by this:
这可以通过以下方式减少到我想要的程度4.2.10：
bash --version | grep "bash" | cut -f 4 -d " " | cut -d "-" -f 1 | cut -d "(" -f 1
However, this feels like it would be prone to break if that message ever changed slightly for whatever reason.
但是，如果该消息因任何原因稍有更改，则感觉它很容易中断。
Is there a better way to do this, and what is this better way?
有没有更好的方法来做到这一点，这个更好的方法是什么？
回答by Mansoor Siddiqui
If you're running within a bash shell, then the $BASH_VERSIONenvironment variable should be set:
如果您在 bash shell 中运行，$BASH_VERSION则应设置环境变量：
$ echo $BASH_VERSION
4.2.8(1)-release
That should be easier and more reliable to parse. See the man pagefor a list of environment variables set by the shell.
这应该更容易和更可靠地解析。有关shell 设置的环境变量列表，请参阅手册页。
回答by FelixEnescu
There's also a special array (BASH_VERSINFO) containing each version number in separate elements.
还有一个特殊的数组 (BASH_VERSINFO) 在单独的元素中包含每个版本号。
if ((BASH_VERSINFO[0] < 3))
then
echo "Sorry, you need at least bash-3.0 to run this script."
exit 1
fi
See http://www.tldp.org/LDP/abs/html/internalvariables.htmlfor more info:
有关更多信息，请参阅http://www.tldp.org/LDP/abs/html/internalvariables.html：
# Bash version info:
for n in 0 1 2 3 4 5
do
echo "BASH_VERSINFO[$n] = ${BASH_VERSINFO[$n]}"
done
# BASH_VERSINFO[0] = 3 # Major version no.
# BASH_VERSINFO[1] = 00 # Minor version no.
# BASH_VERSINFO[2] = 14 # Patch level.
# BASH_VERSINFO[3] = 1 # Build version.
# BASH_VERSINFO[4] = release # Release status.
# BASH_VERSINFO[5] = i386-redhat-linux-gnu # Architecture
# (same as $MACHTYPE).
回答by kev
To extract the first part:
提取第一部分：
$ echo ${BASH_VERSION%%[^0-9.]*}
4.2.10
回答by jogojapan
There seems to be an environment variable for this:
似乎有一个环境变量：
echo $BASH_VERSION
yields
产量
4.1.7(1)-release
on my machine.
在我的机器上。
回答by codeforester
Building more on Bluecat's great answer, here is a function that checks for just the major version or a combination of major and minor versions and returns 0 if the current bash version is >= the needed version:
在Bluecat 的好答案上构建更多内容，这里有一个函数，它只检查主要版本或主要和次要版本的组合，如果当前 bash 版本 >= 所需版本，则返回 0：
check_bash_version() {
local major=${1:-4}
local minor=
local rc=0
local num_re='^[0-9]+$'
if [[ ! $major =~ $num_re ]] || [[ $minor && ! $minor =~ $num_re ]]; then
printf '%s\n' "ERROR: version numbers should be numeric"
return 1
fi
if [[ $minor ]]; then
local bv=${BASH_VERSINFO[0]}${BASH_VERSINFO[1]}
local vstring=$major.$minor
local vnum=$major$minor
else
local bv=${BASH_VERSINFO[0]}
local vstring=$major
local vnum=$major
fi
((bv < vnum)) && {
printf '%s\n' "ERROR: Need Bash version $vstring or above, your version is ${BASH_VERSINFO[0]}.${BASH_VERSINFO[1]}"
rc=1
}
return $rc
}
It can be invoked as:
它可以被调用为：
check_bash_version 4 # check if 4.0 or above
check_bash_version 4 2 # check if 4.2 or above
See the assertion related to this:
请参阅与此相关的断言：
回答by codeforester
runbash --versionthen its output likes
运行bash --version然后它的输出喜欢
GNU bash, version 3.2.25(1)-release (x86_64-redhat-linux-gnu)
or
或者
GNU bash, version 4.1.2(1)-release (x86_64-redhat-linux-gnu)
or
或者
GNU bash, version 4.3.30(1)-release (x86_64-pc-linux-gnu)
usebash variable $BASH_VERSION, run echo $BASH_VERSION, its output likes
使用bash 变量$BASH_VERSION，运行echo $BASH_VERSION，它的输出喜欢
4.3.30(1)-release
UsuallyI use command sedto extract the version no., following is concrete command:
通常我使用命令sed来提取版本号，以下是具体命令：
bash --version | sed -r -n 's@.*version (.*)\(1\)-release.*@\1@p'
bash --version | sed -r -n 's@.*version (.*)\(1\)-release.*@\1@p'
eg:
例如：
[flying@lempstacker ~]$ bash --version | sed -r -n 's@.*version (.*)\(1\)-release.*@@p'
4.2.46
[flying@lempstacker ~]$
echo $BASH_VERSION | sed -r -n 's@(.*)\(1\)-release.*@\1@p'
echo $BASH_VERSION | sed -r -n 's@(.*)\(1\)-release.*@\1@p'
eg:
例如：
[flying@lempstacker ~]$ echo $BASH_VERSION | sed -r -n 's@(.*)\(1\)-release.*@@p'
4.2.46
[flying@lempstacker ~]$
回答by mklement0
Building on bluecat's helpful answer:
To report the first 3 version-number components - e.g., 4.2.10- via built-in array shell variable BASH_VERSINFO:
要报告前 3 个版本号组件 - 例如4.2.10- 通过内置数组 shell 变量BASH_VERSINFO：
$ bash -c 'IFS=.; echo "${BASH_VERSINFO[*]: 0:3}"'
4.2.10
If you're calling this from inside a Bash script, use a subshellin order to localize the effect of changing IFS:
如果您从 Bash 脚本内部调用它，请使用子shell以本地化更改的效果IFS：
#!/usr/bin/env bash
ver=$(IFS=.; echo "${BASH_VERSINFO[*]: 0:3}") # -> e.g., $ver == '4.2.10'
Explanation:
解释：
IFS=.sets the internal field separator to., which ensures that when we print an array inside a double-quoted string later, the array's elements are joined with that separator.- Note that you can't just do
IFS=. echo ...to transiently redefine IFS scoped to the theechocommand, because shell parameter expansion(the expansion of${BASH_VERSINFO[*]: 0:3}, in this case) happens beforeechois invoked. Therefore, two separate command are needed; the use of a command substitution($(...)) ensures that the change toIFSis still localized, because command substitutions run in subshells.
- Note that you can't just do
${BASH_VERSINFO[*]: 0:3}extracts the first 3 elements from array variable$BASH_VERSINFO(starting at index0, return3elements).- Note that in order for
IFSto work as intended,*rather than@must be used to reference the array;@would invariablyseparate the elements with a single space each, irrespective of the value of$IFS.
- Note that in order for
IFS=.将内部字段分隔符设置为.，这确保当我们稍后在双引号字符串中打印数组时，数组的元素与该分隔符连接。${BASH_VERSINFO[*]: 0:3}从数组变量中提取前 3 个元素$BASH_VERSINFO（从 index 开始0，返回3元素）。- 请注意，为了
IFS按预期工作，*而不是@必须使用来引用数组；@将总是元件与每个单个空格分开的值无关，$IFS。
- 请注意，为了
