Why would the command "ls *" generate an error about invalid options?

Question

There is a thread that talks about ls "*" not showing any files, but I actually wonder why the simple

ls *

command doesn't output anything in my terminal other than

ls: invalid option -- '|'
Try 'ls --help' for more information.

while

ls

will list all the files in the current directories as

 1                  ferol                      readme.txt
 2                  fichier                    sarku
 2018               GameShell                  Templates
 22223333          '-|h4k3r|-'                 test
 3                  hs_err_pid2301.log         test2
 CA.txt             important.top.secret.txt   toto.text
 CA.zip             JavaBlueJProject           tp1_inf1070
 countryInfo.txt    liendur                   'tp1_inf1070_A19(2) (1)'
 currency           liensymbolique             tp1_inf1070_A19.tar
 curreny            LOL                        Videos
 Desktop            Longueuil                 'VirtualBox VMs'
 Documents          Music                      words
 douffos            numbers                    Zip.zip
 Downloads          Pictures
 examples.desktop   Public

Any ideas as to why the globbing doesn't take effect here? I'm on Ubuntu, working in the terminal, I don't know if it makes a difference.

Thanks.

Answer 1

When you run

ls *

globbing takes effect as usual, and the * expands to all filenames in the current directory -- including this one:

-|h4k3r|-

That starts with a -, so ls tries to parse it as an option (like -a or -l). As | isn't actually an option recognized by ls, it complains with the error message invalid option, then exits (without listing any files).

If you want to list everything in the current folder explicitly, instead try

ls ./*

...which will prefix all filenames with ./ (so that entry will not be misinterpreted as an option), or

ls -- *

...where -- is the "delimiter indicating end of options", ie. any remaining arguments are filenames.

Answer 2

I think the important missing conceptual leap here is where the globbing is done. ls will never do any globbing itself. If you don't give it any arguments, it assumes you meant . and lists out that directory like it would any directory you gave it on the command line.

The thing that does the globbing is the shell. The shell then passes the results as a bunch of command line arguments to ls. ls has no clue if you typed those arguments, or if they are the result of a glob expansion. And so it parses them for flags like it would any other command line arguments.

This isn't how it works on Windows, which I think is a major flaw in how Windows handles command line programs.

One other interesting demonstration here is to make a directory that has a bunch of directories in it. If you then do ls * there, the shell will give all those directories as arguments, and ls will give you a listing for each of them. This just shows that assuming . if you didn't provide an argument is a simple default, not any kind of special behavior.

If you say ./* instead of * the shell will do a glob expansion that results in everything having ./ in front of it, so ls won't interpret any of the arguments as options. If you do ls -- *, ls interprets the option -- as meaning it should cease trying to process options and treat all the rest of the arguments as files or directories it should give a listing for. So, IMHO, -- is the better choice.

The -- convention is followed by the vast majority of Unix command line utilities and is a standard feature of most argument parsing libraries written for most languages.

Answer 3

Generally the command ls * should list all the files and directories in your current working directory. There are 2 cases that would lead to the issue you are facing.

1. If any of the files contained in the Directory have unsupported characters, such as a directory named --2 “or -2 would lead to such an error. For example:

   # ls -la | grep 2$
   drwxrwxr-x  2 test test    4096 Oct 28 14:58 --2
   # ls *
   ls: unrecognized option '--2'
   

   This is because the file name starting with - will be considered as an option to the ls command.

2. If that’s not the case, I believe that there may be some alias set in your .bashrc file. For example, if I set the alias alias ls='ls –2', I would not be able to use the ls command as it will call for an invalid option which is -2.

Answer 4

It means you have a file named '-|'. Because of the way the shell (bash, ksh, ...) works, all wildcard expressions are evaluated against what is in your current directory before the command is called, so if you have a file called -|, then ls * will be called as ls file1 file2 ... -| ..., and you get this error.

As for how to delete or rename it - you can use mv './-|' xyz to rename it to xyz, for example.