Run Control File

Xonsh allows you to customize your shell behavior with run control files, called “xonshrc” files. These files are written either in the Xonsh language (a superset of Python) or in Python and are executed exactly once at startup.

The control file usually contains:

  • Assignment statements setting environment variables. This includes standard OS environment variables that affect other programs and many that Xonsh uses for itself.

  • xontrib commands to load selected add-ins (”xontribs<tutorial_xontrib.html#loading-xontribs>”).

  • Xonsh function definitions.

  • Alias definitions, many of which invoke the above functions with specified arguments.

First of all, you need to know about the home directory ~/.xonshrc control file. This file is commonly used to put configurations for the user interactive prompt and it is executed automatically only for interactive Xonsh sessions.

There are also a few places where Xonsh looks for run control files. These files will be executed automatically in both interactive and non-interactive modes, and you need to use the $XONSH_INTERACTIVE and $XONSH_LOGIN environment variables to determine what code you want to execute in each mode. Here is the list of run control files and directories:

  • Cross-desktop group (XDG) compliant ~/.config/xonsh/rc.xsh control file.

  • The system-wide control file /etc/xonsh/xonshrc for Linux and OSX and in %ALLUSERSPROFILE%\xonsh\xonshrc on Windows. It controls options that are applied to all users of Xonsh on a given system.

  • The home-based directory ~/.config/xonsh/rc.d/ and system /etc/xonsh/rc.d/ can contain .xsh files. They will be executed at startup in order. This allows for drop-in configuration where your configuration can be split across scripts and common and local configurations more easily separated.

In addition:

  • Use xonsh --no-rc to prevent using control files.

  • Use xonsh --rc snail.xsh to run only a certain control file.

  • Use xonsh -i script.xsh to run xonsh in interactive mode with loading all possible control files.

  • Use xonsh --rc rc1.xsh rc2.xsh -- script.xsh to run scripts with multiple control files.

The options set per user override settings in the system-wide control file.

Xonsh provides 2 wizards to create your own “xonshrc”. xonfig web provides basic settings, and xonfig wizard steps you through all the available options.

xonfig web

This helps you choose a color theme, customized prompt and add-in packages (“xontribs”). It initializes your personal run control file (usually at ~/.xonshrc). To invoke it (from a xonsh prompt):

>>> xonfig web
Web config started at 'http://localhost:8421'. Hit Crtl+C to stop.
127.0.0.1 - - [23/Aug/2020 15:04:39] "GET / HTTP/1.1" 200 -

This will open your default browser on a page served from a local server. You can exit the server by typing Ctrl+c at any time.

The page has:

Colors:

shows the color themes built into Xonsh. Simply click on a sample to select it. Although color names are standardized across various terminal applications, their actual appearance is not and do vary widely. Seeing is believing!

Prompts:

shows various sample prompts. It is recommended to select one but to then edit the xonshrc file to further refine your prompt.

Xontribs:

are community-contributed add-ins often used to enhance command completion and line editing, but can affect any aspect of Xonsh behavior. Choose one or more to suit your needs but note that they will require installation of additional packages. You can extend Xonsh by writing your own xontrib, and are invited/urged to do so!

Save:

Click to write the configuration choices to your ~/.xonshrc. This will add a few tagged lines to your run control file, but will not overwrite it completely, so you can run xonfig web at any time.

xonfig wizard

This imports settings and tools you have defined in your existing (ordinary) shell such as bash. It also walks you through setting all known environment variables and xontribs in a question-and-answer format:

@ xonfig wizard

          Welcome to the xonsh configuration wizard!
          ------------------------------------------
This will present a guided tour through setting up the xonsh static
config file. Xonsh will automatically ask you if you want to run this
wizard if the configuration file does not exist. However, you can
always rerun this wizard with the xonfig command:

    @ xonfig wizard

This wizard will load an existing configuration, if it is available.
Also never fear when this wizard saves its results! It will create
a backup of any existing configuration automatically.

This wizard has two main phases: foreign shell setup and environment
variable setup. Each phase may be skipped in its entirety.

For the configuration to take effect, you will need to restart xonsh.

'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'``-.,_,.-*'

To exit the wizard at any time, press Ctrl-C.


'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'

                      Foreign Shell Setup
                      -------------------
The xonsh shell has the ability to interface with foreign shells such
as Bash, or zsh (fish not yet implemented).

For configuration, this means that xonsh can load the environment,
aliases, and functions specified in the config files of these shells.
Naturally, these shells must be available on the system to work.
Being able to share configuration (and source) from foreign shells
makes it easier to transition to and from xonsh.

Add a new foreign shell, yes or no [default: no]? yes
shell name (e.g. bash): bash
interactive shell [bool, default=True]:
login shell [bool, default=False]:
env command [str, default='env']:
alias command [str, default='alias']:
extra command line arguments [list of str, default=[]]:
safely handle exceptions [bool, default=True]:
pre-command [str, default='']:
post-command [str, default='']:
foreign function command [str, default=None]:
source command [str, default=None]: source
Foreign shell added.

Add a new foreign shell, yes or no [default: no]? no

'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'`-.,_,.-*'``-.,_,.-*'

                  Environment Variable Setup
                  --------------------------
The xonsh shell also allows you to setup environment variables from
the static configuration file. Any variables set in this way are
superseded by the definitions in the xonshrc or on the command line.
Still, setting environment variables in this way can help define
options that are global to the system or user.

The following lists the environment variable name, its documentation,
the default value, and the current value. The default and current
values are presented as pretty repr strings of their Python types.

Note: Simply hitting enter for any environment variable
will accept the default value for that entry.

Would you like to set env vars now, yes or no [default: no]? yes

$ALLUSERSPROFILE

default value:
current value: 'C:\\ProgramData'
>>>

$APPDATA

default value:
current value: 'C:\\Users\\bobhy\\AppData\\Roaming'
>>>

$AUTO_CD
Flag to enable changing to a directory by entering the dirname or
full path only (without the cd command).
default value: False
current value: False
>>>

. . .

Real world sample xonshrc

The following is a real-world example of such a file.

Download xonshrc

# adjust some paths
$PATH.append('/home/scopatz/sandbox/bin')
$LD_LIBRARY_PATH = ['/home/scopatz/.local/lib', '/home/scopatz/miniconda3/lib', '']

# alias to quit AwesomeWM from the terminal
def _quit_awesome(args, stdin=None):
    lines = $(ps ux | grep "gnome-session --session=awesome").splitlines()
    pids = [l.split()[1] for l in lines]
    for pid in pids:
        kill @(pid)

aliases['qa'] = _quit_awesome

# some customization options, see https://xon.sh/envvars.html for details
$MULTILINE_PROMPT = '`·.,¸,.·*¯`·.,¸,.·*¯'
$XONSH_SHOW_TRACEBACK = True
$XONSH_STORE_STDOUT = True
$XONSH_HISTORY_MATCH_ANYWHERE = True
$COMPLETIONS_CONFIRM = True
$XONSH_AUTOPAIR = True

See also xontrib-rc-awesome.

Real world sample rc.py

The following is a real-world example of such a file. This can be set by env XONSHRC=rc.py xonsh or xonsh --rc=rc.py

Download rc.py

from xonsh.built_ins import XSH

env = XSH.env
# adjust some paths
env["PATH"].append("/home/scopatz/sandbox/bin")
env["LD_LIBRARY_PATH"] = ["/home/scopatz/.local/lib", "/home/scopatz/miniconda3/lib"]

# alias to quit AwesomeWM from the terminal
def _quit_awesome(args, stdin=None):
    print("awesome python code")


XSH.aliases["qa"] = _quit_awesome
# setting aliases as list are faster since they don't involve parser.
XSH.aliases["gc"] = ["git", "commit"]

# some customization options, see https://xon.sh/envvars.html for details
env["MULTILINE_PROMPT"] = "`·.,¸,.·*¯`·.,¸,.·*¯"
env["XONSH_SHOW_TRACEBACK"] = True
env["XONSH_STORE_STDOUT"] = True
env["XONSH_HISTORY_MATCH_ANYWHERE"] = True
env["COMPLETIONS_CONFIRM"] = True
env["XONSH_AUTOPAIR"] = True

Snippets for xonshrc

The following are useful snippets and code that tweaks and adjust xonsh in various ways. If you have any useful tricks, feel free to share them.

Adjust how git branch label behaves

Xonsh adds a colored branch name to the prompt when working with git or hg repositories. This behavior can be controlled with the $PROMPT environment variable. See how to customize the prompt . The branch name changes color if the work dir is dirty or not. This is controlled by the {branch_color} formatter string.

The following snippet reimplements the formatter also to include untracked files when considering if a git directory is dirty.

from xonsh.prompt.vc import git_dirty_working_directory
$PROMPT_FIELDS['branch_color'] = lambda: ('{BOLD_INTENSE_RED}'
                                               if git_dirty_working_directory(include_untracked=True)
                                               else '{BOLD_INTENSE_GREEN}')

Get better colors from the ls command

The colors of the ls command may be hard to read in a dark terminal. If so, this is an excellent addition to the xonshrc file.

$LS_COLORS='rs=0:di=01;36:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:'

Make JSON data directly pastable

With the following snippet, xonsh will understand JSON data such as { "name": "Tyler", "active": false, "age": null }. Note that, though practical, this is rather hacky and might break other functionality. Use at your own risk.

import builtins
builtins.true = True
builtins.false = False
builtins.null = None

Display different date information every 10th time

For a compact shell prompts, some people prefer a very condensed time format. But when you have a lengthy shell session you might want the date to show up in your logs every now and then…

import time
def get_shelldate():
    get_shelldate.fulldate %= 10
    get_shelldate.fulldate += 1
    if get_shelldate.fulldate == 1:
        return time.strftime('%d%m%Y')
    return time.strftime('%H:%M')
get_shelldate.fulldate = 0

$PROMPT_FIELDS['shelldate'] = get_shelldate