Easy command-line interpreters with cmd and cmd2¶
author: | Catherine Devlin |
---|---|
date: | 2010-02-20 |
slides: | http://pypi.python.org/pypi/cmd2 |
Web 2.0¶
Defining CLI¶
Also known as
- “Line-oriented command interpreter”
- “Command-line interface”
- “Shell”
- Accepts free text input at prompt
- Outputs lines of text
- (repeat)
Examples¶
-
class
big
¶ - Bash, Korn, zsh
- Python shell
- screen
- Zork
- SQL clients: psql, SQL*Plus, mysql...
- ed
!= Command Line Utilities¶
-
class
big
(
ls
,grep
,ping
, etc.)- Accept arguments at invocation
- execute
- terminate
Use
sys.argv
,optparse
Decide your priorities¶
A cmd
app: pirate.py¶
from cmd import Cmd
class Pirate(Cmd):
pass
pirate = Pirate()
pirate.cmdloop()
do_
-methods: pirate2.py¶
class Pirate(Cmd):
gold = 3
def do_loot(self, arg):
'Seize booty frrrom a passing ship.'
self.gold += 1
print('Now we gots {0} doubloons'
.format(self.gold))
def do_drink(self, arg):
'Drown your sorrrows in rrrum.'
self.gold -= 1
print('Now we gots {0} doubloons'
.format(self.gold))
Hooks: pirate3.py¶
def do_loot(self, arg):
'Seize booty from a passing ship.'
self.gold += 1
def do_drink(self, arg):
'Drown your sorrrows in rrrum.'
self.gold -= 1
def precmd(self, line):
self.initial_gold = self.gold
return line
def postcmd(self, stop, line):
if self.gold != self.initial_gold:
print('Now we gots {0} doubloons'
.format(self.gold))
Arguments: pirate4.py¶
def do_drink(self, arg):
'''Drown your sorrrows in rrrum.
drink [n] - drink [n] barrel[s] o' rum.'''
try:
self.gold -= int(arg)
except:
if arg:
print('''What's "{0}"? I'll take rrrum.'''
.format(arg))
self.gold -= 1
quitting: pirate5.py¶
def postcmd(self, stop, line):
if self.gold != self.initial_gold:
print('Now we gots {0} doubloons'
.format(self.gold))
if self.gold < 0:
print("Off to debtorrr's prison.")
stop = True
return stop
def do_quit(self, arg):
print("Quiterrr!")
return True
prompts, defaults: pirate6.py¶
prompt = 'arrr> '
def default(self, line):
print('What mean ye by "{0}"?'
.format(line))
Other CLI packages¶
-
class
big
- CmdLoop
- cly
- CMdO
- pycopia
- cmdlin
- cmd2
Demo¶
-
class
huge
Convert
cmd
app tocmd2
cmd2¶
But wait, there’s more¶
- Abbreviated commands
- Shell commands
- Quitting
- Timing
- Echo
- Debug
Minor changes: pirate7.py¶
default_to_shell = True
multilineCommands = ['sing']
terminators = Cmd.terminators + ['...']
songcolor = 'blue'
settable = Cmd.settable + 'songcolor Color to ``sing`` in (red/blue/green/cyan/magenta, bold, underline)'
Cmd.shortcuts.update({'~': 'sing'})
def do_sing(self, arg):
print(self.colorize(arg, self.songcolor))
Now how much would you pay?¶
options / flags
Quiet (suppress feedback)
BASH-style select
Parsing: terminators, suffixes
Options: pirate8.py¶
@options([make_option('--ho', type='int', default=2,
help="How often to chant 'ho'"),
make_option('-c', '--commas',
action="store_true",
help="Intersperse commas")])
def do_yo(self, arg, opts):
chant = ['yo'] + ['ho'] * opts.ho
separator = ', ' if opts.commas else ' '
chant = separator.join(chant)
print('{0} and a bottle of {1}'
.format(chant, arg))
Serious example: sqlpython¶
-
class
big
cmd
-based app by Luca Canali @ CERNReplacement for Oracle SQL*Plus
Now
cmd2
-based; postgreSQL; MySQL
File reporter¶
-
class
huge
Gather info: Python
Store: postgresql
Report: html
fileutil.py¶
import glob
import os.path
for fullfilename in glob.glob('/home/cat/proj/cmd2/*.py'):
(dirpath, fname) = os.path.split(fullfilename)
stats = os.stat(fullfilename)
binds['path'] = dirpath
binds['name'] = fname
binds['bytes'] = stats.st_size
cmd("""INSERT INTO cat.files (path, name, bytes)
VALUES (%(path)s, %(name)s, %(bytes)s)""")
quit()
sqlpython features¶
-
class
big
- from
cmd2
: scripts, redirection, py, etc. - multiple connections
- UNIX: ls, cat, grep
- Special output
- from