= xonsh cheatsheet

$PROMPT         prompt spec
$X              value of variable X
${X}            let Y be value of X, value of variable Y will be returned
${'HO' + 'ME'}  get ENV HOME
${...}          is ENV dict
$PATH.append(x) append x to $PATH

$(CMD…)         run CMD in subprocess. stdout & err captured. return stdout
!(CMD…)         run CMD in subprocess. stdout & err captured. return xonsh.__amalgam__.CommandPipeline
   .stdout.getvalue()      binary stdout
   .out                    UTF-8 stdout
   .stderr.getvalue()      binary stderr
   .out                    UTF-8 stderr
   .returncode             exit code
   .starttime              start timestamp as UNIX epoch
   .endtime                end timestamp as UNIX epoch
$[CMD…]         run CMD in subprocess. stdout & err to terminal. return None
![CMD…]         run CMD in subprocess. stdout & err to terminal. return xonsh.__amalgam__.CommandPipeline
@(CODE…)        evaluate python CODE in shell context (return list to space-join them for proc call)
@$(CMD)                    @([i.strip() for i in $(cmd).split()]), i.e. execute CMD and whitespace-split elements to create a list
CMD1 and CMD2              run CMD2 only if CMD1.returncode==0
CMD1 or CMD2               run CMD2 only if CMD1.returncode!=0
`REGEX`                    regex matching files; returns list of strings
g`GLOB`                    globbing pattern matching files; returns list of strings
g`PATTERN`                 regex or globbing pattern matching Path; returns list of Paths
IDENTIFIER?                help(IDENTIFIER)

CMD out> FILE              redirect stdout of CMD to FILE
CMD err> FILE              redirect stderr of CMD to FILE
CMD all> FILE              redirect stdout & stderr of CMD to FILE
CMD < FILE                 read stdin of CMD from FILE

CMD; <Ctrl-Z>; fg          suspend exec of CMD; contiue with fg
jobs                       list running jobs


$RAISE_SUBPROC_ERROR = True        “set -e” equivalent
$EXPAND_ENV_VARS = False           disable ENV replacement in CMDs
$XONSH_TRACE_SUBPROC = True        subprocess debugging
with ${...}.swap(SOMEVAR='foo'):   context manager to set ENV var temporarily