fish-shell/doc_src/faq.hdr

/** \page faq Frequently asked questions

- <a href='#faq-cwd-symlink'>Why does cd, pwd and other fish commands always resolve symlinked directories to their canonical path?</a>
- <a href='#faq-cd-autocomplete'>Why does the cd command autocompletion list the subdirectories of my home directory as completions?</a>
- <a href='#faq-cd-implicit'>I accidentally entered a directory path and fish changed directory. What happened?</a>
- <a href='#faq-open'>The open command doesn't work.</a>
- <a href='#faq-default'>How do I make fish my default shell?</a>
- <a href='#faq-titlebar'>I'm seeing weird output before each prompt when using screen. What's wrong?</a>
- <a href='#faq-greeting'>How do I change the greeting message?</a>
- <a href='#faq-history'>Why doesn't history substitution ("!$" etc.) work?</a>

<hr>

\section faq-cwd-symlink Why does cd, $PWD and and various fish commands always resolve symlinked directories to their canonical path?

<i>
For example if ~/images is a symlink to ~/Documents/Images, if I write
'cd images', my prompt will say ~/D/Images, not ~/images.
</i>

Because it is impossible to consistently keep symlinked directories
unresolved. It is indeed possible to do this partially, and many other
shells do so. But it was felt there are enough serious corner cases
that this is a bad idea. Most such issues have to do with how '..' is
handled, and are varitations of the following example:

Writing <code>cd images; ls ..</code> given the above directory
structure would list the contents of ~/Documents, not of ~, even
though using <code>cd ..</code> changes the current directory to ~,
and the prompt, the pwd builtin and many other directory information
sources suggest that the current directory is ~/images and its
parent is ~. This issue is not possible to fix without either making
every single command into a builtin, breaking Unix semantics or
implementing kludges in every single command.

This issue can also be seen when doing IO redirection.

Another related issue is that many programs that operate on recursive
directory trees, like the find command, silently ignore symlinked
directories. For example, <code>find $PWD -name '*.txt'</code>
silently fails in shells that don't resolve symlinked paths.

<hr>

\section faq-cd-autocomplete Why does the cd command autocompletion list the subdirectories of my home directory as completions?

Because they are completions. In fish, if you specify a relative
directory to the cd command, i.e. any path that does not start with
either './' or '/', the environment variable CDPATH will be examined, and any
directories in this path is used as a base directory. To disable this
feature, write <code>set CDPATH .</code> on the commandline.

<hr>

\section faq-cd-implicit I accidentally entered a directory path and fish changed directory. What happened?

If fish is unable to locate a command with a given name, fish will
test if a directory of that name exists. If it does, it is implicitly
assumed that you want to change working directory. For example, the
fastest way to switch to your home directory is to simply press
<code>~</code> and enter.

<hr>

\section faq-open The open command doesn't work.

The open command uses the mimetype database and the .desktop files
used by Gnome and KDE to identify filetypes and default actions. If
at least one of these two desktops are installed, but the open command is
not working, this probably means that the relevant files are installed
in a nonstandard location. Please contact the <a
href='mailto:fish-users@lists.sf.net'>fish mailing list</a>, and
hopefully this can be resolved.

<hr>

\section faq-default How do I make fish my default shell?

If you installed fish manually (e.g. by compiling it, not by using a
package manager), you first need to add fish to the list of shells by
executing the following command (assuming you installed fish in
/usr/local) as root:


<code>echo /usr/local/bin/fish >>/etc/shells</code>

If you installed a prepackaged version of fish, the package manager
should have already done this for you.

In order to change your default shell, type:

<code>chsh -s /usr/local/bin/fish</code>

You may need to adjust the above path to e.g. \c /usr/bin/fish. Use the command <code>which fish</code> if you are unsure of where fish is installed.

Unfortunately, there is no way to make the changes take effect at once.
You will need to log out and back in again.

<hr>

\section faq-titlebar I'm seeing weird output before each prompt when using screen. What's wrong?

Quick answer:

Run the following command in fish:

<pre>
echo 'function fish_title;end' &gt; ~/.config/fish/config.fish
</pre>

Problem solved!

The long answer:

Fish is trying to set the titlebar message of your terminal. While
screen itself supports this feature, your terminal does
not. Unfortunately, when the underlying terminal doesn't support
setting the titlebar, screen simply passes through the escape codes
and text to the underlying terminal instead of ignoring them. It is
impossible detect and resolve this problem from inside fish since fish
has no way of knowing what the underlying terminal type is. For now,
the only way to fix this is to unset the titlebar message, as
suggested above.

Note that fish has a default titlebar message, which will be used if
the fish_title function is undefined. So simply unsetting the
fish_title function will not work.

<hr>

\section faq-greeting How do I change the greeting message?

Change the value of the variable fish_greeting. For example, to remove
the greeting use:

<pre>
set fish_greeting
</pre>

<hr>

\section faq-history Why doesn't history substitution ("!$" etc.) work?

Because history substitution is an awkward interface that was invented before
interactive line editing was even possible.  Fish drops it in favor of
perfecting the interactive history recall interface.  Switching requires a
small change of habits: if you want to modify an old line/word, first recall
it, then edit.  E.g. don't type "sudo !!" - first press Up, then Home, then
type "sudo ".

Fish history recall is very simple yet effective:

 - As in any modern shell, the Up arrow recalls whole lines, starting from the last line executed.  A single press replaces "!!", later presses replace "!-3" and the like.
    - If the line you want is far back in the history, type any part of the line and then press Up one or more times.  This will constrain the recall to lines that include this text, and you will get to the line you want much faster.  This replaces "!vi", "!?bar.c" and the like.
 - Alt+Up recalls individual arguments, starting from the last argument in the last line executed.  A single press replaces "!$", later presses replace "!!:4" and the like.
    - If the argument you want is far back in history (e.g. 2 lines back - that's a lot of words!), type any part of it and then press Alt+Up.  This will show only arguments containing that part and you will get what you want much faster.  Try it out, this is very convenient!
    - If you want to reuse several arguments from the same line ("!!:3*" and the like), consider recalling the whole line and removing what you don't need (Alt+D and Alt+Backspace are your friends).

See <a href='index.html#editor'>documentation</a> for more details about line editing in fish.

*/