CODEWITHSUNDEEP
pythonread-eval-print-loop
user3.1415927
user3.1415927

Reputation: 367

Does Python(2.7)'s interactive shell have an equivalent to bash's "!!" (bang bang)?

I'm used to typing !! in bash when I want to reference the last command executed in that shell.

$ ls -la  
drwxr-xr-x   4 me  wheel    136 Jan 19  2013 wireshark_stuff  
... (etc) ...  
-rw-r--r--   1 me  wheel     11 Mar 13 13:51 old_PS1  
$ !! |grep for_something_in_those_results  
ls -la |grep for_something_in_those_results  
/grep_results

Is there a way to do this in python?

>>> complicated_dict.['long_key_name'][0]  
(response)  
>>> my_func(!!)

This would get really handy as the interpreter commands become increasingly complicated. Sure, I could just use a plethora of local variables - but sometimes it's handy to just invoke the last thing run...

Upvotes: 3

Views: 166

Answers (4)

Chris Johnson
Chris Johnson

Reputation: 21996

Up-arrow / return! As long as your interpreter was compiled with readline support.

Upvotes: 0

chepner
chepner

Reputation: 531948

Using default Readline bindings, Control-P + Enter is probably the closest exact equivalent to !!; the first key fetches the previous command; the second executes it. You can probably add a custom binding to .inputrc to execute both functions with one keystroke. Note, though, this is entirely line-oriented; if you try to use this following a multi-line for statement, for example, you'll only get the very last line of the body, not the entire for statement.

The _ variable stores the result of the last evaluated expression; it doesn't reevaluate, though. This can be seen most clearly with something like datetime.datetime.now:

>>> datetime.datetime.now()
datetime.datetime(2018, 3, 22, 14, 14, 50, 360944)
>>> datetime.datetime.now()
datetime.datetime(2018, 3, 22, 14, 14, 51, 665947)
>>> _
datetime.datetime(2018, 3, 22, 14, 14, 51, 665947)
>>> _
datetime.datetime(2018, 3, 22, 14, 14, 51, 665947)
>>> _
datetime.datetime(2018, 3, 22, 14, 14, 51, 665947)
>>> datetime.datetime.now()
datetime.datetime(2018, 3, 22, 14, 14, 58, 404816)

Upvotes: 1

user3483203
user3483203

Reputation: 51165

You can use the _ character to reference the last calculated value, and use it in other calculations:

>>> x = 5
>>> x + 10
15
>>> _
15
>>> _ + 2
17

Upvotes: 4

Daniel Roseman
Daniel Roseman

Reputation: 599856

The value of the last expression evaluated in the Python shell is available as _, ie the single underscore.

Upvotes: 4

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