blocks|key|2549913|text|如果您想要做的就是创建一个相对路径更改最少的绝对路径，那么一个简单、安全和快速的方法就是：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2549914|[[+$dest_dir+==+/*+]]+%7C%7C+dest_dir=$PWD/$dest_dir|code-block|syntax|javascript|2549915|(有关dest_dir优于DEST_DIR的原因，请参阅Correct+Bash+and+shell+script+variable+capitalization。)|offset|length|style|CODE|2549916|即使目录不存在(还没有)，或者不可能通过cd连接到它(例如，因为它的权限不允许)，上面的代码仍然可以工作。它可能会产生带有冗余‘’的路径。组件，'..‘组件和冗余斜杠(`/a//b'，'//a/b/'，...)。|2549917|如果你想要一个最低限度的清理路径(保留符号链接未解析)，那么原始代码的修改版本可能是一个合理的选择：|2549918|dest_dir=$(cd+--+"$dest_dir"/+&&+pwd)|2549919|对于处理以‘-’开头的目录名，必须使用|2549920|+--。对于处理包含空格(实际上是$IFS字符)的名称，必须使用|unordered-list-item|2549921|+"$dest_dir"中的引号。对于处理相对名称仅为-.|2549922|Plain的目录，"$dest_dir"/中的引号是必需的。pwd就足够了，因为它的行为就像默认情况下指定了D20。|2549923|2549924|请注意，如果cd失败，代码会将dest_dir设置为空字符串。在对该变量做任何其他操作之前，您可能需要检查一下。|2549925|还要注意的是，$(cd+...)将使用Bash创建子外壳。这在某种程度上是好的，因为之后不需要cd回到起始目录(这可能是不可能的)，但如果你做得太多(例如在循环中)，这可能会导致性能问题。|2549926|最后，请注意，如果目录名包含一个或多个尾随换行符(例如，由mkdir+$'dir\n'创建的)，则代码将不起作用。有可能解决这个问题(如果你真的关心它的话)，但它很混乱。参见How+to+avoid+bash+command+substitution+to+remove+the+newline+character?和shell:+keep+trailing+newlines+('\n')+in+command+substitution。一种可能的方法是：|2549927|dest_dir=$(cd+--+"$dest_dir"/+&&+printf+'%25s.'+"$PWD")++++#+Add+a+trailing+'.'
dest_dir=${dest_dir%25.}+++++++++++++++++++++++++++++++++++#+Remove+the+trailing+'.'|2549928|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/q/673055/4154375|1|https://stackoverflow.com/q/15184358/4154375|2|https://unix.stackexchange.com/q/383217/264812^0|0|0|3|8|D|8|S|1H|0|0|K|2|0|0|0|0|1|2|H|4|0|1|B|R|1|0|9|C|U|3|0|0|6|2|F|8|0|7|9|1B|2|0|T|E|2F|1Z|1|4F|1O|2|0|0^^$0|@$1|2|3|4|5|6|7|1M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1O|8|@$I|1P|J|1Q|K|L]|$I|1R|J|1S|K|L]]|9|@$I|1T|J|1U|1|1V]]|A|$]]|$1|M|3|N|5|6|7|1W|8|@$I|1X|J|1Y|K|L]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|20|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|21|8|@]|9|@]|A|$]]|$1|U|3|V|5|W|7|22|8|@$I|23|J|24|K|L]|$I|25|J|26|K|L]]|9|@]|A|$]]|$1|X|3|Y|5|W|7|27|8|@$I|28|J|29|K|L]|$I|2A|J|2B|K|L]]|9|@]|A|$]]|$1|Z|3|10|5|W|7|2C|8|@$I|2D|J|2E|K|L]|$I|2F|J|2G|K|L]]|9|@]|A|$]]|$1|11|3|-4|5|6|7|2H|8|@]|9|@]|A|$]]|$1|12|3|13|5|6|7|2I|8|@$I|2J|J|2K|K|L]|$I|2L|J|2M|K|L]]|9|@]|A|$]]|$1|14|3|15|5|6|7|2N|8|@$I|2O|J|2P|K|L]|$I|2Q|J|2R|K|L]]|9|@]|A|$]]|$1|16|3|17|5|6|7|2S|8|@$I|2T|J|2U|K|L]]|9|@$I|2V|J|2W|1|2X]|$I|2Y|J|2Z|1|30]]|A|$]]|$1|18|3|19|5|D|7|31|8|@]|9|@]|A|$E|F]]|$1|1A|3|-4|5|6|7|32|8|@]|9|@]|A|$]]]|1B|$1C|$5|1D|1E|1F|A|$1G|1H]]|1I|$5|1D|1E|1F|A|$1G|1J]]|1K|$5|1D|1E|1F|A|$1G|1L]]]]

If all you want to do is to make an absolute path that has minimal changes from a relative path then a simple, safe, and fast way to to it is:

<pre><code>[[ $dest_dir == /* ]] || dest_dir=$PWD/$dest_dir
</code></pre>

(See <a href="https://stackoverflow.com/q/673055/4154375">Correct Bash and shell script variable capitalization</a> for an explanation of why <code>dest_dir</code> is preferable to <code>DEST_DIR</code>.)

The code above will work even if the directory doesn't exist (yet) or if it's not possible to <code>cd</code> to it (e.g. because its permissions don't allow it). It may produce paths with redundant '.' components, '..' components, and redundant slashes (`/a//b', '//a/b/', ...).

If you want a minimally cleaned path (leaving symlinks unresolved), then a modified version of your original code may be a reasonable option:

<pre><code>dest_dir=$(cd -- "$dest_dir"/ &amp;&amp; pwd)
</code></pre>

<ul>
<li>The <code>--</code> is necessary to handle directory names that begin with '-'.</li>
<li>The quotes in <code>"$dest_dir"</code> are necessary to handle names that contain whitespace (actually <code>$IFS</code> characters) or glob characters.</li>
<li>The trailing slash on <code>"$dest_dir"/</code> is necessary to handle a directory whose relative name is simply <code>-</code>.</li>
<li>Plain <code>pwd</code> is sufficient because it behaves as if <code>-L</code> was specified by default.</li>
</ul>

Note that the code will set <code>dest_dir</code> to the empty string if the <code>cd</code> fails. You probably want to check for that before doing anything else with the variable.

Note also that <code>$(cd ...)</code> will create a subshell with Bash. That's good in one way because there's no need to <code>cd</code> back to the starting directory afterwards (which may not be possible), but it could cause a performance problem if you do it a lot (e.g. in a loop).

Finally, note that the code won't work if the directory name contains one or more trailing newlines (e.g. as created by <code>mkdir $'dir\n'</code>). It's possible to fix the problem (in case you really care about it), but it's messy. See <a href="https://stackoverflow.com/q/15184358/4154375">How to avoid bash command substitution to remove the newline character?</a> and <a href="https://unix.stackexchange.com/q/383217/264812">shell: keep trailing newlines ('\n') in command substitution</a>. One possible way to do it is:

<pre><code>dest_dir=$(cd -- "$dest_dir"/ &amp;&amp; printf '%s.' "$PWD") # Add a trailing '.'
dest_dir=${dest_dir%.} # Remove the trailing '.'
</code></pre>

I have written bash scripts that accept a directory name as an argument. A single dot ('.') is a valid directory name, but I sometimes need to know where '.' is. The <code>readlink</code> and <code>realpath</code> commands provide a resolved path, which does not help because I need to allow for symbolic links.

For example, the resolved path to the given directory might be something like <code>/mnt/vol_01/and/then/some</code>, whereas the script is called with '.' where '.' is <code>/app/then/some</code> (a sym link which would resolve to the first path I gave).

What I have done to solve my problem is use <code>cd</code> and <code>pwd</code> in combination to provide the full path I want, and it seems to have worked OK so far.

A simplified example of a script:

<pre><code>DEST_DIR=$1

# Convert the given destination directory to a full path, ALLOWING 
# for symbolic links. This is necessary in cases where '.' is 
# given as the destination directory.
DEST_DIR=$(cd $DEST_DIR &amp;&amp; pwd -L)

# Do stuff in $DEST_DIR
</code></pre>

My question is: is my use of <code>cd</code> and <code>pwd</code> the best way to get what I want? Or is there a better way?

How to obtain the full PATH, *allowing* for symbolic links

我已经编写了接受目录名作为参数的bash脚本。单点('.')是一个有效的目录名，但我有时需要知道'.‘是。readlink和realpath命令提供了一个已解析的路径，这没有什么帮助，因为我需要允许符号链接。例如，给定目录的解析路径可能类似于/mnt/vol_01/and/then/some，而脚本使用'.‘调用。其中...

问如何获取完整路径，允许符号链接
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