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A shell power-up for working with the file system and running subprocess commands.

Project description

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A shell power-up for working with the file system and running subprocess commands.

Features

  • Run and define subprocess commands

    • run

    • cmd

  • Interact with files

    • atomicdfile, atomicdir

    • read, readchunks, readlines

    • write, writechunks

    • fsync, dirsync

  • Execute core shell operations

    • cp, mv, mkdir, touch

    • rm, rmfile, rmdir

    • ls, lsfiles, lsdirs

    • walk, walkfiles, walkdirs

  • Other utilities

    • backup

    • cd

    • environ

    • cwd, homedir

    • and more!

  • 100% test coverage

  • Fully type-annotated

  • Python 3.6+

Quickstart

Install using pip:

pip3 install shelmet

Import the sh module:

import shelmet as sh

Run system commands:

# sh.run() is a wrapper around subprocess.run() that defaults to output capture, text-mode,
# exception raising on non-zero exit codes, environment variable extension instead of
# replacement, and support for passing command arguments as a variable number of strings instead
# of just a list of strings.
result = sh.run("ps", "aux")
print(result.stdout)
print(result.stderr)

# stdout and stderr can be combined with...
result = sh.run("some", "command", combine_output=True)

# or not captured at all...
sh.run("...", capture_output=False)

Create reusable run commands that support chained commands like “pipe” | , “and” &&, “or” ||, and “after” ;:

# sh.cmd() returns a sh.Command object that can be used to execute a fixed command.
ps_aux = sh.cmd("ps", "aux")

# And has the option to pipe it's output into another command automatically.
grep_ps = ps_aux.pipe("grep", "-i", check=False)
print(grep_ps.shell_cmd)
# ps aux | grep -i

search_result_1 = grep_ps.run("search term 1")
print(search_result_1.stdout)

search_result_2 = grep_ps.run("search term 2")
print(search_result_2.stdout)

# Equivalent to: mkdir foo && echo 'success' || echo 'failure'
sh.cmd("mkdir", "foo").and_("echo", "success").or_("echo", "failure").run()

Perform file system operations:

# Make directories and sub-directories. Behaves like "$ mkdir -p"
sh.mkdir("a", "b", "c", "d/e/f/g")

# Context-manager to change working directory temporarily. Behaves like "$ cd".
with sh.cd("d/e/f/g"):
    sh.touch("1.txt", "2.txt", "3.txt")

    # Move files or directories. Works across file-systems. Behaves like "$ mv".
    sh.mv("1.txt", "11.txt")

    # Copy files or directories. Behaves like "$ cp -r"
    sh.cp("2.txt", "22.txt")

    # List top-level directory contents.
    # NOTE: sh.ls() and its siblings are generators.
    list(sh.ls())

    # Limit to files.
    list(sh.lsfiles())

    # Limit to directories.
    list(sh.lsdirs())

    # Remove files.
    sh.rmfile("11.txt", "22.txt", "3.txt")
    # Or use sh.rm which handles both files and directories.
    sh.rm("11.txt", "22.txt", "3.txt")

# Recursively walk current directory.
# NOTE: sh.walk() and its siblings are generators.
list(sh.walk())

# Or just a specified directory.
list(sh.walk("d"))

# Or just it's files or directories.
list(sh.walkfiles())
list(sh.walkdirs())

# Remove directories.
sh.rmdir("a", "b", "c", "d")
# Or use sh.rm which handles both files and directories.
sh.rm("a", "b", "c", "d")

Perform file IO:

sh.write("test.txt", "some text\n")
sh.write("test.txt", " some more text\n", "a")

sh.write("test.bin", b"some bytes")
sh.write("test.bin", b" some more bytes", "ab")

sh.writelines("output.txt", ["1", "2", "3"])              # -> "1\n2\n3\n"
sh.writelines("output.txt", (str(i) for i in range(10)))  # -> "0\n1\n2\n3\n4\n5\n6\n7\n8\n9\n"

# Write to a file atomically. See sh.atomicfile for more details.
sh.write("test.txt", "content", atomic=True)
sh.writelines("test.txt", ["content"], atomic=True)

text = sh.read("test.txt")        # -> "some text\nsome more text\n"
data = sh.read("text.bin", "rb")  # -> b"some bytes some more bytes"

for line in sh.readlines("test.txt"):
    print(line)

for chunk in sh.readchunks("test.txt", size=1024):
    print(chunk)

sh.write("test.txt", "a|b|c|d")
items = list(sh.readchunks("test.txt", sep="|"))
print(items)  # -> ["a", "b", "c", "d"]

sh.write("test.txt", b"a|b|c|d", "wb")
assert "".join(sh.readchunks("test.txt", "rb", sep=b"|")) == b"a|b|c|d"

Backup files:

backup_file = sh.backup("test.txt")
print(backup_file)                                     # test.txt.2021-02-24_16-19-20-276491~
sh.backup("test.txt", utc=True)                        # test.txt.2021-02-24T11:19:20.276491Z~
sh.backup("test.txt", epoch=True)                      # test.txt.1614878783.56201
sh.backup("test.txt", suffix=".bak")                   # test.txt.2021-02-24T16:19:20.276491.bak
sh.backup("test.txt", suffix=".bak", timestamp=False)  # test.txt.bak
sh.backup("test.txt", prefix="BACKUP_", suffix="")     # BACKUP_test.txt.2021-02-24T16:19:20.276491

from functools import partial
import itertools

counter = itertools.count(1)
backup = partial(sh.backup, namer=lambda src: f"{src.name}-{next(counter)}~")
backup("test.txt")  # test.txt-1~
backup("test.txt")  # test.txt-2~
backup("test.txt")  # test.txt-3~

Write to a new file atomically where content is written to a temporary file and then moved once finished:

import os

with sh.atomicfile("path/to/atomic.txt") as fp:
    # Writes are sent to a temporary file in the same directory as the destination.
    print(fp.name) # will be something like "path/to/.atomic.txt_XZKVqrlk.tmp"
    fp.write("some text")
    fp.write("some more text")

    # File doesn't exist yet.
    assert not os.path.exists("path/to/atomic.txt")

# Exiting context manager will result in the temporary file being atomically moved to destination.
# This will also result in a lower-level fsync on the destination file and directory.
assert os.path.exists("path/to/atomic.txt")

# File mode, sync skipping, and overwrite flag can be specified to change the default behavior which is...
with sh.atomicfile("file.txt", "w", skip_sync=False, overwrite=True) as fp:
    pass

# Additional parameters to open() can be passed as keyword arguments.
with sh.atomicfile("file.txt", "w", **open_kwargs) as fp:
    pass

# To writie to a file atomically without a context manager
sh.write("file.txt", "content", atomic=True)

Create a new directory atomically where its contents are written to a temporary directory and then moved once finished:

with sh.atomicdir("path/to/atomic_dir") as atomic_dir:
    # Yielded path is temporary directory within the same parent directory as the destination.
    # path will be something like "path/to/.atomic_dir_QGLDfPwz_tmp"
    some_file = atomic_dir / "file.txt"
    some_file.write_text("contents")  # file written to "path/to/.atomic_dir_QGLDfPwz_tmp/file.txt"

    some_dir = atomic_dir / "dir"
    some_dir.mkdir()  # directory created at "path/to/.atomic_dir_QGLDfPwz_tmp/dir/"

    # Directory doesn't exist yet.
    assert not os.path.exists("path/to/atomic_dir")

# Exiting context manager will result in the temporary directory being atomically moved to destination.
assert os.path.exists("path/to/atomic_dir")

# Sync skipping and overwrite flag can be specified to change the default behavior which is...
with sh.atomicdir("atomic_dir", skip_sync=False, overwrite=True) as atomic_dir:
    pass

Temporarily change environment variables:

# Extend existing environment.
with sh.environ({"KEY1": "value1", "KEY2": "value2"}) as new_environ:
    # Do something while environment changed.
    # Environment variables include all previous ones and {"KEY1": "value1", "KEY2": "value2"}.
    pass

# Replace the entire environment with a new one.
with sh.environ({"KEY": "value"}, replace=True):
    # Environment variables are replaced and are now just {"KEY": "value"}.
    pass

For more details, please see the full documentation at https://shelmet.readthedocs.io.

Changelog

v0.5.0 (2020-03-04)

  • Import all utility functions into shelmet namespace.

  • Remove shelmet.sh catch-all submodule in favor of splitting it into smaller submodules, shelmet.filesystem and shelmet.path. Recommend using import shelmet as sh as primary usage pattern instead of importing submodules. breaking change

  • Add functions:

    • backup

    • read

    • readbytes

    • readchunks

    • readlines

    • readtext

    • write

    • writebytes

    • writelines

    • writetext

v0.4.0 (2021-01-26)

  • Rename sh.command to sh.cmd. breaking change

  • Add methods to sh.Command / sh.command:

    • Command.and_

    • Command.or_

    • Command.after

v0.3.0 (2020-12-24)

  • Add to sh module:

    • Command

    • command

    • cwd

    • homedir

    • run

v0.2.0 (2020-11-30)

  • Add to sh module:

    • atomicdir

  • Rename atomic_write to atomicfile. breaking change

v0.1.0 (2020-11-16)

  • First release.

  • Add sh module:

    • atomic_write

    • cd

    • cp

    • dirsync

    • environ

    • fsync

    • getdirsize

    • ls

    • lsdirs

    • lsfiles

    • mkdir

    • mv

    • reljoin

    • rm

    • rmdir

    • rmfile

    • touch

    • umask

    • walk

    • walkdirs

    • walkfiles

MIT License

Copyright (c) 2020 Derrick Gilland

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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