shell-proc 2.2.0

Continuous shell process

Install

pip install shell_proc

2.0.0 Changes

This library has recently been updated to support commands with stdin prompts. I noticed git and ssh would occasionally request pompt input from the user for authorization. The old approach would get the exit code by sending an echo to stdin. This would give the echo command as a user prompt. To support this a lot of things had to change. Windows users will notice some changes.

• I changed how the echo results works and am using “;” instead of a second command passed into stdin.

• I also changed the pipes to non-blocking allowing input prompts to be read.

  • Before the pipe reading waited on a newline.

• Unfortunately, “;” did not really work with windows cmd.

  • Windows operations were changed to use powershell.

  • Powershell $? gives “True” or “False”, so it does not give a proper exit_code.

  • Old cmd is still supported if you pass use_old_cmd=True into the Shell. Not guaranteed to work.

• Added input which will only pass values into stdin without expecting a command to finish.

Run

Run a series of commands with results.

from shell_proc import Shell

with Shell() as sh:
    sh('cd ..')
    if sh.is_windows():
        cmd = sh('dir')
    else:
        cmd = sh('ls')

    # cmd (Command) Attributes: cmd, exit_code, stdout, stderr
    print(cmd.stdout)

Run a series of terminal commands.

import sys
from shell_proc import Shell

with Shell(stdout=sys.stdout, stderr=sys.stderr) as sh:
    sh.run('mkdir storage')
    sh('cd storage')  # Same as sh.run()
    sh('echo Hello World! > hello.txt')

    if sh.is_windows():
        sh('python -m venv ./winvenv')
        sh('./winvenv/Scripts/activate.bat')
    else:
        pwd = sh('pwd')
        sh('cd ~')
        sh('python3 -m venv ./lxvenv')
        sh('source ./lxvenv/bin/activate')
        sh('cd {}'.format(pwd.stdout))
    sh('pip install requests')
    sh('pip list')

table = '|{:_<20}|{:_<20}|{:_<20}|{:_<50}|'
print(table.format('', '', '', '').replace('|', '_'))
print(table.format("Exit Code", "Has Error", "Has Ouput", "Command").replace('_', ' '))
print(table.format('', '', '', ''))
for cmd in sh.history:
    print(table.format(cmd.exit_code, cmd.has_error(), cmd.has_output(), cmd.cmd).replace('_', ' '))
print(table.format('', '', '', '').replace('|', '_'))

Run without blocking every command

import sys
import time
from shell_proc import Shell

with Shell(stdout=sys.stdout, stderr=sys.stderr, blocking=False, wait_on_exit=True) as sh:
    sh.run('mkdir storage')
    sh('cd storage')  # Same as sh.run()
    sh('echo Hello World! > hello.txt')

    if sh.is_windows():
        sh('python -m venv ./winvenv')
        sh('./winvenv/Scripts/activate.bat')
    else:
        pwd = sh('pwd')
        sh('cd ~')
        sh('python3 -m venv ./lxvenv')
        sh('source ./lxvenv/bin/activate')
        sh('cd {}'.format(pwd.stdout))
    sh('pip install requests')
    sh('pip list')
    print('---------- At exit (shows non-blocking until exit) ----------')

time.sleep(1)
print('1 Second has passed', 'Running:', sh.current_command)
time.sleep(1)
print('2 Seconds have passed', 'Running:', sh.current_command)
time.sleep(1)
print('3 Seconds have passed', 'Running:', sh.current_command)

sh.wait()  # Wait for all commands to finish

Manually call commands and check results.

import io
import sys
from shell_proc import Shell

# Initialize and run tasks
sh = Shell('mkdir storage',
           'cd storage',
           'echo Hello World! > hello.txt',
           stderr=io.StringIO())

# Manually run tasks
if sh.is_windows():
    sh('python -m venv ./winvenv')
    sh('./winvenv/Scripts/activate.bat')
else:
    pwd = sh('pwd')
    sh('cd ~')
    sh('python3 -m venv ./lxvenv')
    sh('source ./lxvenv/bin/activate')
    sh('cd {}'.format(pwd.stdout))

# Not exactly success. If True no output was printed to stderr. Stderr could also be warning like need to update pip
results = sh.run('pip install requests')
print("***** Successful install: ", results.exit_code == 0)
if results.exit_code != 0:
    sh.stderr.seek(0)  # Move to start of io.StringIO()
    err = sh.stderr.read()  # All text collected into stderr from subprocess stderr
    print(err, file=sys.stderr)
    # sh.print_stderr()  # Also available

sh.stdout = io.StringIO()  # Start saving output for new tasks
results = sh('pip list')
print('***** Output Printed\n', results.stdout)

sh('pip -V')
print('pip -V =>', sh.last_command.stdout)

print('All collected stdout')
sh.stdout.seek(0)  # Move to start of io.StringIO()
print(sh.stdout.read(), end='', flush=True)  # Print all read data

# Should close when finished to stop threads from reading stdout and stderr subprocess.PIPE
# (will close automatically eventually)
sh.close()

io.StringIO() Help

Below are several functions to read data from stdout and io.StringIO()

def read_io(fp):
    """Return all of the human readable text from the io object."""
    try:
        if fp.seekable():
            fp.seek(0)
        out = fp.read()
        if not isinstance(out, str):
            out = out.decode('utf-8')
        return out
    except:
        return ''

def clear_io(fp):
    """Try to clear the stdout"""
    text = read_io(fp)
    try:
        fp.truncate(0)
    except:
        pass
    return text

def print_io(fp, end='\n', file=None, flush=True):
    """Print and clear the collected io."""
    if file is None:
        file = sys.stdout
    print(clear_io(fp), file=file, flush=True)

Run Python

Added support to call python in a subprocess

from shell_proc import Shell

with Shell(python_call='python3') as sh:
    sh.python('-c',
              'import os',
              'print("My PID:", os.getpid())')

Run Parallel

Added support to run parallel subprocesses

import sys
import time
from shell_proc import Shell, python_args

with Shell(stdout=sys.stdout, stderr=sys.stderr) as sh:
    p = sh.parallel(*(python_args('-c',
                'import os',
                'import time',
                "print('My ID:', {id}, 'My PID:', os.getpid(), time.time())".format(id=i)) for i in range(10)))
    sh.wait()  # or p.wait()
    print('finished parallel')
    time.sleep(1)

    tasks = []
    for i in range(10):
        if i == 3:
            t = python_args('-c',
                'import os',
                'import time',
                'time.sleep(1)',
                "print('My ID:', {id}, 'My PID:', os.getpid(), time.time())".format(id=i))
        else:
            t = python_args('-c',
                'import os',
                'import time',
                "print('My ID:', {id}, 'My PID:', os.getpid(), time.time())".format(id=i))
        tasks.append(t)
    p = sh.parallel(*tasks)
    p.wait()
    print('finished parallel')
    time.sleep(1)

    with sh.parallel() as p:
        for i in range(10):
            if i == 3:
                p.python('-c',
                         'import os',
                         'import time',
                         'time.sleep(1)',
                         "print('My ID:', {id}, 'My PID:', os.getpid(), time.time())".format(id=i))
            else:
                p.python('-c',
                         'import os',
                         'import time',
                         "print('My ID:', {id}, 'My PID:', os.getpid(), time.time())".format(id=i))
        # p.wait() on exit context
    print('finished parallel')

Use Pipe

The pipe operator can be used with Command objects to take a completed command stdout and submit the text into a new commands stdin.

import sys
from shell_proc import Shell, ShellExit, shell_args

with Shell(stdout=sys.stdout, stderr=sys.stderr) as sh:
    # One step
    results = sh('dir') | 'find "run"'  # Hard to tell where find output starts

    # Two Steps
    cmd = sh('dir')
    results = cmd | 'find "run"'

Input Prompts

As of version 2.0.0, Shell can work with input prompts. I noticed git and ssh would occasionally request pompt input from the user for authorization. I wanted to support this use case.

Input prompt code

# prompt_me.py
print("Greetings!")
name = input("Hello, who am I talking to? ")
print(f"It\'s nice to meet you {name!r}")

Shell code

# run shell
import sys
from shell_proc import Shell

with Shell(stdout=sys.stdout, stderr=sys.stderr) as sh:
    print("Give user input when prompted")
    # Need block=False or will wait forever for input it cannot receive
    sh("python prompt_me.py", block=False)

    # Get actual input from user
    value = input()

    # Send input to stdin (without expecting this to run as a command)
    # This will finish the first command sh(python prompt_me.py)
    sh.input(value)
    sh.wait()  # Manually wait for sh(python prompt_me.py) to finish

    # Test again
    sh("python prompt_me.py", block=False)
    sh.input("John Doe", wait=True)

# Shell.__exit__ will wait for final exit_code from sh(python prompt_me.py)
print("Exited successfully!")

Output. Note, “Jane Doe” was entered in as input.

Give user input when prompted
Greetings!
Hello, who am I talking to? Jane Doe
It's nice to meet you 'Jane Doe'
Greetings!
Hello, who am I talking to? It's nice to meet you 'John Doe'
Exited successfully!