As you have probably figured out by now, xonsh is not sh-lang compliant. If your muscles have memorized all of the Bash prestidigitations, this page will help you put a finger on how to do the equivalent task in xonsh.
For shell scripts, the recommended file extension is xsh, and shebang line is #!/usr/bin/env xonsh.
| Bash | Xonsh | Notes |
|---|---|---|
$NAME or ${NAME} |
$NAME |
Look up an environment variable by name. |
export NAME=Peter |
$NAME = 'Peter' |
Setting an environment variable. See also $UPDATE_OS_ENVIRON <update_os_environ>. |
unset NAME |
del $NAME |
Unsetting/deleting an environment variable. |
echo "$HOME/hello" |
echo "$HOME/hello" |
Construct an argument using an environment variable. |
something/$SOME_VAR/$(some_command) |
@('something/' + $SOME_VAR + $(some_command).strip()) |
Concatenate a variable or text with the result of running a command. |
${!VAR} |
${var or expr} |
Look up an environment variable via another variable name. In xonsh, this may be any valid expression. |
$(cmd args) or `cmd args` |
@$(cmd args) |
Command substitution (allow the output of a command to replace the command itself). Tokenizes and executes the output of a subprocess command as another subprocess. |
set -e |
$RAISE_SUBPROC_ERROR = True |
Cause a failure after a non-zero return code. Xonsh will raise a supbrocess.CalledProcessError. |
set -x |
trace on and $XONSH_TRACE_SUBPROC = True |
Turns on tracing of source code lines during execution. |
&& |
and or && |
Logical-and operator for subprocesses. |
|| |
or as well as || |
Logical-or operator for subprocesses. |
$? |
_.rtn |
Returns the exit code, or status, of the previous command. |
N=V command |
with ${...}.swap(N=V): command |
Set temporary environment variable(s) and execute for command. Use an indented block to execute many commands in the same context. |
!$ |
__xonsh__.history[-1, -1] |
Get the last argument of the last command |
$<n> |
$ARG<n> |
Command line argument at index n, so $ARG1 is the equivalent of $1. |
$@ |
$ARGS |
List of all command line argument and parameter strings. |
shopt -s dotglob |
$DOTGLOB = True |
Globbing files with “” or “*” will also match dotfiles, or those ‘hidden’ files whose names begin with a literal ‘.’. Such files are filtered out by default like in bash. |
| Display completions as list | $COMPLETIONS_DISPLAY = 'readline' |
Display completions will emulate the behavior of readline. |
exit |
sys.exit() |
Exiting from the current script. |
To understand how xonsh executes the subprocess commands try to set $XONSH_TRACE_SUBPROC <xonsh_trace_subproc> to True:
>>> $XONSH_TRACE_SUBPROC = True
>>> echo $(echo @('hello')) @('wor' + 'ld') | grep hello
TRACE SUBPROC: (['echo', 'hello'],)
TRACE SUBPROC: (['echo', 'hello\n', 'world'], '|', ['grep', 'hello'])