readlink
Created by : Mr Dk.
2023 / 04 / 12 19:55
Hangzhou, Zhejiang, China
Background
readlink 用于打印符号链接的内容。
Usage
$ readlink --help
Usage: readlink [OPTION]... FILE...
Print value of a symbolic link or canonical file name
-f, --canonicalize canonicalize by following every symlink in
every component of the given name recursively;
all but the last component must exist
-e, --canonicalize-existing canonicalize by following every symlink in
every component of the given name recursively,
all components must exist
-m, --canonicalize-missing canonicalize by following every symlink in
every component of the given name recursively,
without requirements on components existence
-n, --no-newline do not output the trailing delimiter
-q, --quiet,
-s, --silent suppress most error messages
-v, --verbose report error messages
-z, --zero separate output with NUL rather than newline
--help display this help and exit
--version output version information and exit
GNU coreutils online help: <http://www.gnu.org/software/coreutils/>
For complete documentation, run: info coreutils 'readlink invocation'
ChatGPT 给出的资料：
The readlink command in Linux is used to print the symbolic link value of a given file or directory. It can also be used to resolve multiple levels of symbolic links, showing the final destination of a chain of symbolic links.
Demo
An Existing Target
创建一个指向实际存在文件的符号链接。
$ touch target.txt
$ ln -s target.txt l1
直接使用 readlink，将会打印符号链接中保存的实际值：
$ readlink l1
target.txt
加入 -f 参数可以打印全路径，前提是 最后一级之前 的所有路径都存在：
$ readlink -f l1
/home/mrdrivingduck/target.txt
Non-existing Target
创建一个指向实际不存在文件的符号链接。
$ ln -s bbb l2
此时，使用 -f 参数依旧可以打印结果，因为最后一级之前的所有路径已存在，最后一级的文件不存在。
$ readlink -f l2
/home/mrdrivingduck/bbb
-m 参数也可以打印结果，因为它会忽略缺失文件：
$ readlink -m l2
/home/mrdrivingduck/bbb
-e 参数将无法打印结果，因为它要求目标必须存在。加上 -v 参数可以显示错误信息：
$ readlink -e l2
$ readlink -e -v l2
readlink: l2: No such file or directory