shelmet 0.6.0

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

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

Links

• Project: https://github.com/dgilland/shelmet

• Documentation: https://shelmet.readthedocs.io

• PyPI: https://pypi.python.org/pypi/shelmet/

• Github Actions: https://github.com/dgilland/shelmet/actions

Features

• Run and define subprocess commands

  • run

  • cmd

• Interact with files

  • atomicdfile, atomicdir

  • read, readchunks, readlines, readtext, readbytes

  • write, writechunks, writelines, writetext, writebytes

  • fsync, dirsync

• Execute core shell operations

  • cp, mv, mkdir, touch

  • rm, rmfile, rmdir

  • ls, lsfiles, lsdirs

  • walk, walkfiles, walkdirs

• Archive and backup files

  • archive, unarchive, lsarchive

  • backup

• Other utilities

  • 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 return iterables.
    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 return iterables.
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(5)))  # -> "0\n1\n2\n3\n4\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:

# Create backup as copy of file.
backup_file = sh.backup("a.txt")
print(backup_file)                                  # a.txt.2021-02-24T16:19:20.276491~
sh.backup("a.txt", utc=True)                        # a.txt.2021-02-24T11:19:20.276491Z~
sh.backup("a.txt", epoch=True)                      # a.txt.1614878783.56201
sh.backup("a.txt", suffix=".bak")                   # a.txt.2021-02-24T16:19:20.276491.bak
sh.backup("a.txt", suffix=".bak", timestamp=False)  # a.txt.bak
sh.backup("a.txt", prefix="BACKUP_", suffix="")     # BACKUP_a.txt.2021-02-24T16:19:20.276491

# Create backup as copy of directory.
sh.backup("path/to/dir")                            # path/to/dir.2021-02-24T16:19:20.276491~

# Create backup as archive of file or directory.
sh.backup("b/c", ext=".tar.gz")                    # b/c.2021-02-24T16:19:20.276491.tar.gz
sh.backup("b/c", ext=".tar.bz2")                   # b/c.2021-02-24T16:19:20.276491.tar.bz2
sh.backup("b/c", ext=".tar.xz")                    # b/c.2021-02-24T16:19:20.276491.tar.xz
sh.backup("b/c", ext=".zip")                       # b/c.2021-02-24T16:19:20.276491.zip

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~

Archive files:

# Create tar, tar-gz, tar-bz2, tar-xz, or zip archives.
sh.archive("archive.tar.gz", "/path/to/foo", "/path/to/bar")

# Archive type is inferred from extension in filename but can be explicitly set.
sh.archive("archive", "path", ext=".tbz")

# Files can be filtered with ls, lsfiles, lsdirs, walk, walkfiles, and walkdirs functions.
sh.archive(
    "archive.tgz",
    sh.walk("path", include="*.py"),
     sh.walk("other/path", exclude="*.log"),
 )

# Archive paths can be customized with root and repath arguments.
# root changes the base path for archive members.
sh.archive("archive.txz", "/a/b/c/1", "/a/b/d/2", root="/a/b")
# -> archive members will be "c/1/*" and "d/2/*"
# -> without root, they would be "b/c/1/*" and "b/d/2/*"

# repath renames paths.
sh.archive("archive.zip", "/a/b/c", "/a/b/d", repath={"/a/b/c": "foo/bar"})
# -> archive members: "foo/bar/*" and "b/d/*"

# repath also works with ls* and walk* by matching on the base path.
sh.archive(
    "log-dump.taz",
    sh.walk("path/to/logs", include="*.log*"),
    repath={"path/to/logs": "logs"},
)

Get list of archive contents:

# Get list of archive contents as PurePath objects.
listing = sh.lsarchive("archive.tgz")

# Use an explicit extension when archive doesn't have one but is supported.
listing = sh.lsarchive("archive", ext=".tgz")

Unarchive tar and zip based archives:

# Extract tar, tar-gz, tar-bz2, tar-xz, or zip archives to directory.
sh.unarchive("archive.tgz", "out/dir")

# Potentially unsafe archives will raise an exception if the extraction path falls outside
# the destination, e.g., when the archive contains absolute paths.
try:
    sh.unarchive("unsafe-archive.tz2", "out")
except sh.ArchiveError:
    pass

# But if an archive can be trusted...
sh.unarchive("unsafe-archive.tz2", "out")

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"

    # file written to "path/to/.atomic_dir_QGLDfPwz_tmp/file.txt"
    some_file.write_text("contents")

    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 atomically move the the temporary directory to the 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": "val1", "KEY2": "val2"}) as new_environ:
    # Do something while environment changed.
    # Environment variables include all previous ones and {"KEY1": "val1", "KEY2": "val2"}.
    pass

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

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

Changelog

v0.6.0 (2021-03-29)

• Change return type for ls, lsfiles, lsdirs, walk, walkfiles, and walkdirs to an iterable class, Ls. Previously, these functions were generators.

• Add option to backup to an archive file in backup.

• Add functions:

  • archive

  • chmod

  • chown

  • lsarchive

  • unarchive

v0.5.0 (2021-03-04)

• 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.