Prompt customizing

[jovanbulck]

Allow a custom prompt. Things todo:

• [x] create new branch
• [x] new prompt "user defined prompt string" built_in shell command
• [x] adapting the char* getprompt(int status) function in jsh.c
  • new definition: char* getprompt(int status, char *user_prompt_string)
  • substituting special symbols in user_prompt_string:
  • %u: username
  • %h: hostname
  • %d: current directory
  • %s: status of last executed command
  • %%: procent sign
• [x] smart truncating the prompt string to a maximum value:
  • e.g. allowing the user to specify a max lenght (eg %l max_value ?) for the cur directory and truncating it to min{curdir, max_value} and if truncated -> delete the beginning of the string until the first '/'

Updated todo list:

Todo for release 1.0:

• [x] testing + code review (pay even more attention to vulnerabilities as the code processes user input ...) on branch CustomizingPrompt
• [x] find a better solution for MAX_DIR_LENGTH. This should be user definable, maybe in the prompt string (as in zsh) or using yet another built_in set or so? Note the MAX_PROMPT_LENGTH can remain hardcoded as we always need a (reasonable) limit for the prompt. When a user tries to set a prompt of more then 100 chars, he's probably hacking :p

Todo for future releases:

• [x] store the user_defined_prompt_string in an environment variable instead of a global variable that is set by a built_in
• [x] user defined coloring for the prompt
• [x] show the username in bold red and/or replace prompt-ending with # when sudo is activated
• [ ] themes
• [ ] more options: e.g. the zsh options
• [ ] the pwd expansion code should detect when the home directory substring and replace it with ~
• [ ] custom prompt things such as git support (would be really cool ;-) )
  • [x] show current git branch
  • [ ] show whether things have changed since last commit
• [ ] the feature-to-undo-all-other-feature-requests is probably to allow the output of any shell command to be included in the prompt.
• [ ] cutting off the path until a user-defined level (e.g. lowest) directory
• [ ] update the man page to document the options for the prompt command

[jovanbulck]

See also https://wiki.gentoo.org/wiki/Zsh/HOWTO#Prompts for an example of how it's done in zsh...

[jovanbulck]

Updated feature requests:

• also include support for coloring the prompt. See jsh-common.h for UNIX tty color escape code definitions && jsh-common.c || mini-grep.c for example uses.
• also include support for pre-made custom 'jsh-themes'. Would be awesome :p

[KevinMordijck]

some code is written, but I'm not sure that the current code does the intended work, some review is welcome. bufferoverflow vulnarabilities are still to be concidered

[jovanbulck]

Good work! Elegant solution for the smart truncation :-)

Some thoughts:

• (in the final version, write a helper function with the for loop and switch)
• TODO MAXDIR_LENGTH isn't independent of MAX_PROMPT_LENGTH, especially is we want this to be user defined. The code will have to calculate the max (worst case) expansion of the user supplied string and then allocate this instead of now statically MAX_PROMPT_LENGTH.
• DONE it's better to use NULL instead of 0´ in the check(ptr != 0)`
• DONE: in the else block the i++ can be illegal: when the user supplied strings ends in a single '%' this will result in a buffer overread (although harmless: the \0 char), I think
• DONE: the function should return a string (e.g. using snprintf), instead of printing one on stdout with printf. As you'll see this messes readline up when using the history arrows....

[jovanbulck]

Status update:

Done:

• prompt built_in that can be used to set the custom prompt (e.g. in the jshrc file)
• custom getprompt() function with %char interpretation and smart truncation of the directory (thanks @KevinMordijck )

See first comment for a full list of things todo --> more ideas --> shout here...

[jovanbulck]

Some info on showing git info in the prompt when the current directory is a git repo (a first proof of concept won't be too hard, I think):

• http://sebastiancelis.com/2009/11/16/zsh-prompt-git-users/ describes the original idea and explains the (zsh) code
• https://github.com/magicmonty/bash-git-prompt is a port of the zsh project to bash and fish; porting it to jsh is probably impossible, but we can maybe re-use some of the script to get the output right...

[GijsTimmers]

What's the status of the issue concerning cutting off the path until the lowest directory?

For example, I'd like this to be my prompt:

[gijs@to-therion samba]$

when I'm in the directory /var/log/samba.

[GijsTimmers]

Other ideas for special symbols in user_prompt_string:

• %i: current local IP address
• %t: current time
• %f: amount of free space in current directory, rounded in gigabytes

[GijsTimmers]

Other ideas for prompt customizing:

%u gets substituted by the username. It would be pretty cool if we could make this username red and bold when the current user is root. It should look like this.

[jovanbulck]

For the prompt coloring: check out the syntax of zsh Apparently bash uses an ugly direct-color-escape-codes syntax, but the page contains lots of examples that can be helpful. Of course you can invent your own better and more elegant syntax, but looking at these example can be a starting point...

Something totally different: the feature-to-undo-all-other-feature-requests is probably to allow the output of any shell command to be included in the prompt. This is possible in zsh and allows really cool things :-) We should think about this...

[jovanbulck]

Hacked in support for user defined coloring of the prompt: check it out at master now :-)

The idea is to use %f{color_name} to turn on non-bold foreground coloring, %F{color_name} for bold/bright foreground text coloring and %b{color_name} for background coloring

e.g. prompt "%F%u%F{reset}@%F{black}%h%F{reset}[%F{cyan}%s%F{reset}]::%d%f{green}%g%f{reset}$ %F{resetall}

Also added support to show the current git branch with %g, if any

Really awesome: check it out

[jovanbulck]

@GijsTimmers I implemented your feature request:

Other ideas for prompt customizing:

%u gets substituted by the username. It would be pretty cool if we could make this username red and bold when the current user is root. It should look like .

Check out the branch sudo_username_red_bold. It should auto detect whether currently sudo is activated (taking into account the timestamps) and print the username red bold. As in:

Looks cool :-)

Try it out and let me know if it works on your system. I have to look a bit further into it before merging in master since it uses sudo -n true and I'm not sure how portable this is (it's not older versions of sudo I think). Moreover some systems don't have sudo installed so I should detect that too. I want this to be configurable in the prompt command in jshrc too

[jovanbulck]

BTW: another idea/option might be to replace the prompt ending $ with a # when sudo is activated

DONE: use the %$ option in the prompt string command

e.g. prompt "%F%u%F{reset}@%F{black}%h%F{reset}[%F{cyan}%s%F{reset}]::%d%f{green}%g%f{reset}%$ %F{resetall}"

[GijsTimmers]

Awesome, and yes, I do like the # / $ thing!

[GijsTimmers]

So my username will stay red as long as jsh remembers that I entered the root credentials?

I think this is a very good feature, security-wise. You kinda wonder why other shells don't do this by default.

[jovanbulck]

So my username will stay red as long as jsh remembers that I entered the root credentials?

I think this is a very good feature, security-wise. You kinda wonder why other shells don't do this by default.

Yes indeed, each time the prompt is refreshed, it checks whether you still have root credentials. I like it too :-)

Check out the updated man page:

%u includes the current username %U includes the current username, colored red and bold iff sudo access is activated %$ includes a '$' char or a '#' char iff sudo access is activated (usefull for the prompt ending)

I'm thinking of creating a more general prompt expansion option, something like %r{chars_to_insert_if_root_access}{chars_to_insert_otherwise} that would allow more general things.

This way a user could opt for having other prompt endings then $ and # or to have other things colored in other colors...

[jovanbulck]

should be stable; merged in master Check it out at work:

Share your thoughts ;-)

prompt customizing

prompt expansion options are fully documented in the man page. Short summary below:

• coloring options for prompt:
  • %B turns on bold; %n restores normal
  • %f{color_name} enables foreground text coloring
  • %F{color_name} enables bold foreground text coloring
  • %b{color_name} enables background coloring
• various new prompt expansion options :
  • %U colors user name red and bold iff sudo activated
  • %$ includes a '$' char or a '#' char iff sudo access is activated
  • %S includes the return value of the last executed shell command, colored red and bold iff non-zero
• directory expansion %d enhancements:
  • truncate the directory to the first char after the first '/' within the cwd (else it looks like the root)
  • replace the current user's home directory with '~' in %d prompt expansion

git support in prompt:

• %g includes the git branch name iff the current working directory is a git repository
• %c includes a bold and red '*' char iff the current working directory is a git repository and git indicates files have changed since the last commit

technical things:

• preprocessing of the prompt color options for max efficiency