cheat/cheat
Chris Lane d8c723681a Graceful failure on failed copy to DEFAULT_CHEAT_DIR
Pull request #108 added the option to automatically copy an
otherwise-uneditable cheatsheet to your DEFAULT_CHEAT_DIR upon an edit
request. This is a minor tweak that implements some graceful failing if
the DEFAULT_CHEAT_DIR does not exist.
2013-11-11 18:10:00 -05:00

321 lines
12 KiB
Python
Executable File

#!/usr/bin/env python
"""
cheat.py -- cheat allows you to create and view interactive cheatsheets on the
command-line. It was designed to help remind *nix system
administrators of options for commands that they use frequently,
but not frequently enough to remember.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
"""
import os
import sys
import argparse
import subprocess
from textwrap import dedent
DEFAULT_CHEAT_DIR = (os.environ.get('DEFAULT_CHEAT_DIR') or
os.path.join(os.path.expanduser('~'), '.cheat'))
USE_PYGMENTS = False
# NOTE remove this check if it is confirmed to work on windows
if os.name == 'posix' and 'CHEATCOLORS' in os.environ:
try:
from pygments import highlight
from pygments.util import ClassNotFound
from pygments.lexers import get_lexer_for_filename, TextLexer
from pygments.formatters import TerminalFormatter
USE_PYGMENTS = True
except ImportError:
pass
def pretty_print(filename):
"""Applies syntax highlighting to a cheatsheet and writes it to stdout"""
try:
if os.path.splitext(filename)[1]:
lexer = get_lexer_for_filename(filename)
else:
# shell is a sensible default when there is no extension
lexer = get_lexer_for_filename(filename + '.sh')
except ClassNotFound:
lexer = TextLexer()
with open(filename) as istream:
code = istream.read()
fmt = TerminalFormatter()
highlight(code, lexer, fmt, sys.stdout)
class CheatSheets(object):
"""Cheatsheets database class."""
dirs = None
sheets = None
def __init__(self):
self.dirs = self.__cheat_directories()
# verify that we have at least one cheat directory
if not self.dirs:
error_msg = ('The {default} dir does not exist'
' or the CHEATPATH var is not set.')
print >> sys.stderr, error_msg.format(default=DEFAULT_CHEAT_DIR)
exit(1)
self.sheets = self.__cheat_files()
def __cheat_directories(self):
"""Assembles a list of directories containing cheatsheets."""
default_directories = [DEFAULT_CHEAT_DIR]
try:
import cheatsheets
default_directories.append(cheatsheets.cheat_dir)
except ImportError:
pass
default = [default_dir for default_dir in default_directories
if os.path.isdir(default_dir)]
if 'CHEATPATH' in os.environ and os.environ['CHEATPATH']:
return [path for path in os.environ['CHEATPATH'].split(os.pathsep)
if os.path.isdir(path)] + default
else:
return default
def __cheat_files(self):
"""
Assembles a dictionary of cheatsheets found in the above directories.
"""
cheats = {}
for cheat_dir in reversed(self.dirs):
cheats.update(dict([(cheat, cheat_dir)
for cheat in os.listdir(cheat_dir)
if not cheat.startswith('.')
and not cheat.startswith('__')]))
return cheats
def edit(self, cheat):
"""Creates or edits a cheatsheet"""
# Assert that the EDITOR environment variable is set and that at least
# 3 arguments have been given
if 'EDITOR' not in os.environ:
print >> sys.stderr, ('In order to create/edit a cheatsheet you '
'must set your EDITOR environment variable '
'to your favorite editor\'s path.')
exit(1)
elif os.environ['EDITOR'] == "":
print >> sys.stderr, ('Your EDITOR environment variable is set '
'to nothing, in order to create/edit a '
'cheatsheet your must set it to a valid '
'editor\'s path.')
exit(1)
else:
editor = os.environ['EDITOR'].split()
# if the cheatsheet already exists, open it for editing
try:
if cheat in self.sheets:
sheet_path = os.path.join(self.sheets[cheat], cheat)
if os.access(sheet_path, os.W_OK):
subprocess.call(editor + [sheet_path])
else:
print >> sys.stderr, ("Sheet '%s' [%s] is not editable."
% (cheat, sheet_path))
print ('Do you want to '
'copy it to your user cheatsheets directory [%s] '
'before editing?\nKeep in mind that your sheet '
'will always be used before system-wide one.'
% DEFAULT_CHEAT_DIR)
awn = raw_input('[y/n] ')
if awn != 'y':
print ('Ok, if you want to edit system-wide sheet, '
'please try `cheat -e <cheatsheet>` '
'again with sudo.')
exit(1)
import shutil
# attempt to copy the cheatsheet to DEFAULT_CHEAT_DIR
try:
new_sheet = os.path.join(DEFAULT_CHEAT_DIR, cheat)
shutil.copy(sheet_path, new_sheet)
subprocess.call(editor + [new_sheet])
# fail gracefully if the cheatsheet cannot be copied. This
# can happen if DEFAULT_CHEAT_DIR does not exist
except IOError:
print ('Could not copy cheatsheet for editing.')
exit(1)
# otherwise, create it
else:
import cheatsheets as cs
# Attempt to write the new cheatsheet to the user's ~/.cheat
# dir if it exists. If it does not exist, attempt to create it.
if os.access(DEFAULT_CHEAT_DIR, os.W_OK) or os.makedirs(DEFAULT_CHEAT_DIR):
subprocess.call(editor
+ [os.path.join(DEFAULT_CHEAT_DIR, cheat)])
# If the directory cannot be created, write to the python
# package directory, though that will likely require the use
# of sudo
else:
if os.access(sheet_path, os.W_OK):
subprocess.call(editor
+ [os.path.join(cs.cheat_dir, cheat)])
else:
error_msg = ("Couldn't create '%s' cheatsheet.\n"
"Please retry usig sudo." % cheat)
print >> sys.stderr, error_msg
exit(1)
except OSError, errno:
print >> sys.stderr, ("Could not launch `%s` as your editor : %s"
% (editor[0], errno.strerror))
exit(1)
def list(self):
"""Lists the cheatsheets that are currently available"""
max_command = max([len(x) for x in self.sheets.keys()]) + 3
return ('\n'.join(sorted(['%s [%s]' % (key.ljust(max_command), value)
for key, value in self.sheets.items()])))
def __parse_cheat_command_block(self, cheat):
"""Parse text blocks inside specified sheet file"""
block = ""
path = os.path.join(self.sheets[cheat], cheat)
with open(path) as cheat_fp:
for line in cheat_fp.readlines():
if line == '\n':
if block:
yield block
block = ""
else:
block += line
if block:
yield block
def search(self, term):
"""Search for a term in sheetcheats"""
for cheat in self.sheets.keys():
output = ''
for block in self.__parse_cheat_command_block(cheat):
if term in block:
if not output:
output = cheat + ":\n"
output += ''.join([" " + line + '\n' for line
in block.split('\n')])
if output:
print output,
# Custom action for argparse
class ListDirectories(argparse.Action):
"""List cheat directories and exit"""
def __call__(self, parser, namespace, values, option_string=None):
print("\n".join(sheets.dirs))
parser.exit()
class ListCheatsheets(argparse.Action):
"""List cheatsheets and exit"""
def __call__(self, parser, namespace, values, option_string=None):
print sheets.list()
parser.exit()
class EditSheet(argparse.Action):
"""If the user wants to edit a cheatsheet"""
def __call__(self, parser, namespace, values, option_string=None):
sheets.edit(values[0])
parser.exit()
class SearchSheet(argparse.Action):
"""If the user wants to search a term inside all cheatsheets"""
def __call__(self, parser, namespace, values, option_string=None):
sheets.search(values[0])
parser.exit()
def main():
"""Main execution function"""
global sheets
sheets = CheatSheets()
desc = dedent('''
cheat allows you to create and view interactive cheatsheets on the
command-line. It was designed to help remind *nix system
administrators of options for commands that they use frequently,
but not frequently enough to remember.''').strip()
epi = dedent('''
Examples:
To look up 'tar':
cheat tar
To create or edit the cheatsheet for 'foo':
cheat -e foo
To list the directories on the CHEATPATH
cheat -d
To list the available cheatsheets:
cheat -l
''').strip()
parser = argparse.ArgumentParser(prog='cheat',
description=desc, epilog=epi,
formatter_class=argparse.
RawDescriptionHelpFormatter)
parser_group = parser.add_mutually_exclusive_group()
parser_group.add_argument('sheet', metavar='cheatsheet',
action='store', type=str, nargs='?',
help='Look at <cheatseet>')
parser_group.add_argument('-e', '--edit', metavar='cheatsheet',
action=EditSheet, type=str, nargs=1,
help='Edit <cheatsheet>')
parser_group.add_argument('-s', '--search', metavar='term',
action=SearchSheet, type=str, nargs=1,
help='Search <term> inside all cheatsheets')
parser_group.add_argument('-l', '--list',
action=ListCheatsheets, nargs=0,
help='List all available cheatsheets')
parser_group.add_argument('-d', '--cheat-directories',
action=ListDirectories, nargs=0,
help='List all current cheat dirs')
args = parser.parse_args()
sheet = args.sheet
# Print the cheatsheet if it exists
if not sheet or sheet in ['help', 'cheat']:
parser.print_help()
elif sheet in sheets.sheets:
filename = os.path.join(sheets.sheets[sheet], sheet)
if USE_PYGMENTS:
pretty_print(filename)
else:
with open(filename) as istream:
for line in istream:
sys.stdout.write(line)
# if it does not, say so
else:
print >> sys.stderr, ('No cheatsheet found for %s.' % sheet)
exit(1)
exit()
if __name__ == '__main__':
main()