### Motivation
There is annoying behavior when you run command in the loop and can't
interrupt e.g. [this
report](https://github.com/xonsh/xonsh/discussions/5371) and a bit
#5342. After diving into this I see the issue around return code.
### The essence
Basically ``p = subprocess.Popen()`` populates ``p.returncode`` after
``p.wait()``, ``p.poll()`` or ``p.communicate()``
([doc](https://docs.python.org/3/library/os.html#os.waitpid)). But if
you're using `os.waitpid()` BEFORE these functions you're capturing
return code from a signal subsystem and ``p.returncode`` will be ``0``
like success but it's not success. So after ``os.waitid`` call you need
to set return code manually ``p.returncode = -os.WTERMSIG(status)`` like
in Popen. Example:
```xsh
python # python interactive
import os, signal, subprocess as sp
p = sp.Popen(['sleep', '100'])
p.pid
# 123
p.wait()
# Ctrl+C or `kill -SIGINT 123` from another terminal
p.returncode
# -2
# BUT:
p = sp.Popen(['sleep', '100'])
p.pid
# 123
pid, status = os.waitpid(p.pid, os.WUNTRACED)
# status=2
# From another terminal:
kill -SIGINT 123
p.wait()
# 0
p.returncode
# 0
```
```xsh
from xonsh.tools import describe_waitpid_status
describe_waitpid_status(2)
# WIFEXITED - False - Return True if the process returning status exited via the exit() system call.
# WEXITSTATUS - 0 - Return the process return code from status.
# WIFSIGNALED - True - Return True if the process returning status was terminated by a signal.
# WTERMSIG - 2 - Return the signal that terminated the process that provided the status value.
# WIFSTOPPED - False - Return True if the process returning status was stopped.
# WSTOPSIG - 0 - Return the signal that stopped the process that provided the status value.
```
See also: [Helpful things for
knight](https://github.com/xonsh/xonsh/pull/5361#issuecomment-2078826181).
### Before
```xsh
$RAISE_SUBPROC_ERROR = True
sleep 100
# Ctrl+C
_.rtn
# 0 # It's wrong and RAISE_SUBPROC_ERROR ignored.
for i in range(5):
print(i)
sleep 5
# 0
# Ctrl+C # Can't interrupt
# 1
# 2
```
### After
```xsh
sleep 100
# Ctrl+C
_.rtn
# -2 # Like in default Popen
$RAISE_SUBPROC_ERROR = True
for i in range(5):
print(i)
sleep 5
# 0
# Ctrl+C
# subprocess.CalledProcessError
```
### Notes
* We need to refactor `xonsh.jobs`. It's pretty uncomfortable work with
module.
* The logic is blurry between Specs, Pipelines and Jobs. We need to
bring more clear functions.
* The `captured` variable looks like "just the way of capturing (stdout,
object)" but in fact it affects all logic very much. We need to create
table where we can see the logic difference for every type of capturing.
E.g. in `captured=stdout` mode we use `xonsh.jobs` to monitor the
command but in `captured=object` we avoid this and some logic from
`xonsh.jobs` applied in `stdout` mode but missed in `object` mode. We
need clear map.
## For community
⬇️ **Please click the 👍 reaction instead of leaving a `+1` or 👍
comment**
---------
Co-authored-by: a <1@1.1>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
* XONSH_TRACE_SUBPROC returns more useful details.
* update
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* Name obj to thread because it's thread!
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* wip
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* wip
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* Added XONSH_SUBPROC_OUTPUT_FORMAT
---------
Co-authored-by: a <1@1.1>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
### Motivation
* To have an ability to manage the output format added ``$XONSH_SUBPROC_OUTPUT_FORMAT`` to switch the way to return the output lines. Default ``stream_lines`` to return text. Alternative ``list_lines`` to return the list of lines. Also supported custom lambda function.
* Additionally the [proposal to change default behavior](https://github.com/xonsh/xonsh/pull/5377#discussion_r1587627131) for a single line case.
* Closes#3924 as soft solution.
### Before
```xsh
mkdir -p /tmp/tst && cd /tmp/tst && touch 1 2 3
$(ls)
# '1\n2\n3\n'
id $(whoami)
# id: ‘pc\n’: no such user: Invalid argument
du $(ls)
# du: cannot access '1'$'\n''2'$'\n''3'$'\n': No such file or directory
ls $(fzf)
# ls: cannot access 'FUNDING.yml'$'\n': No such file or directory
```
### After
```xsh
mkdir -p /tmp/tst && cd /tmp/tst && touch 1 2 3
$XONSH_SUBPROC_OUTPUT_FORMAT = 'list_lines'
$(ls)
# ['1', '2', '3']
[f for f in $(ls)]
# ['1', '2', '3']
id $(whoami)
# uid=501(user) gid=20(staff)
du $(ls)
# 0 1
# 0 2
# 0 3
ls $(fzf)
# FUNDING.yml
# etc
mkdir -p /tmp/@($(whoami))/dir
cat /etc/passwd | grep $(whoami)
```
### Notes
* It will be good to improve parser for cases like `mkdir -p /tmp/$(whoami)/dir`. PR is welcome!
* I named the default mode as `stream_lines` (instead of just `stream` or `raw`) because in fact we transform raw output into stream of lines and possibly reduce the length of output ([replacing `\r\n` to `\n`](c3a12b2a9c/xonsh/procs/pipelines.py (L380-L383))). May be some day we need to add raw "stream" output format.
* Now anybody can implement bash `IFS` behavior in [bashisms](https://github.com/xonsh/xontrib-bashisms).
---------
Co-authored-by: a <1@1.1>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
### Motivation
Basically we use `xonsh --no-rc` to have pure xonsh.
I noticed many times when parent environment can affect `xonsh --no-rc` e.g. `$XONSH_HISTORY_FILE`.
Current workaround is `env -i @$(which xonsh) --no-rc` but I think we need to have pure xonsh way.
Closes#4921
### Before
```xsh
xonsh --no-rc
$QWE = 1
xonsh --no-rc
$QWE
# 1
```
### After
```xsh
xonsh --no-rc
$QWE = 1
xonsh --no-rc --no-env
$QWE
# Unknown environment variable: $QWE
$XONSH_ENV_INHERITED # Marker to have a way to catch this situation.
# False
```
Co-authored-by: a <1@1.1>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Gil Forsyth <gforsyth@users.noreply.github.com>
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* thread details
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