I was rebuilding the bash command ls using C as a unix programming book exercise and had a look at various dir functions. And I realized, that chdir, opendir and similar don't accept pathnames starting with ~ but do accept . or ..
First, why? And second, is the source code of the real unix ls command somewhere visible? Because ls ~ does indeed work and I am curious how this works.
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Lavair
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3The `~` is expanded by the shell. – Ian Abbott Oct 22 '19 at 11:40
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1https://stackoverflow.com/questions/9493234/chdir-to-home-directory – Mat Oct 22 '19 at 11:40
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1"~" is replaced by bash, not evaluated by 'ls' or any other command executed. You can check by calling `echo ~`. But that means if you call your ls from bash, you will get the home directory as command line argument too – Ingo Leonhardt Oct 22 '19 at 11:42
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ahh thanks. Yes that makes sense because I just realized that if I pass ~ as a command line argument, it works – Lavair Oct 22 '19 at 11:43
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1@Lavair: Rather if you pass the expanded value of ~ (which the shell expanded) as a command line argument. – R.. GitHub STOP HELPING ICE Oct 22 '19 at 11:44
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~ is a shell shortcut that expands to the home directory set in /etc/passwd or ldap configuration. The kernel has no concept of home directory and has no idea what ~ directory is.
Maxim Egorushkin
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1Note that if this were not the case, it would be impoissible to create a file whose name is (or begins with) ~. – R.. GitHub STOP HELPING ICE Oct 22 '19 at 11:45
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There's much more: https://www.gnu.org/software/bash/manual/html_node/Tilde-Expansion.html – gstukelj Oct 22 '19 at 11:46
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The ~ is expanded by the shell into the home directory.
You can look up the shell's source code to find the expansion.
S.S. Anne
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