parsing stdout in shell script

Question

Continuation of my initial question:

shell script taking input from python program

So I have standard output from my python program being stored in a variable in my shell script. Now, I have to parse this output so that I can take a substring of the last 22 characters. These are the only ones that matter to me. Unfortunately there's no way to really identify these last characters ("keyword=", etc.), meaning I have to do this completely by their position

would be helpful to show some sample output

glenn jackman
– glenn jackman

2012-08-30 23:53:36 +00:00
Commented Aug 30, 2012 at 23:53 — glenn jackman
– glenn jackman, Commented Aug 30, 2012 at 23:53

chepner · Accepted Answer · 2012-08-30 22:38:49Z

1

Assuming you are using bash, you can use substring expansion:

key=$(python ...)   # From  your previous question

suffix=${key: -22}  # The space between : and - is important

answered Aug 30, 2012 at 22:38

chepner

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gabrtv · Accepted Answer · 2012-09-07 21:43:35Z

1

If you need the last N characters of a string, you can use a simple slice:

>>> v="this is the stdout from my shell command stored in a variable"
>>> v[-22:]
'd stored in a variable'

The last 22 chars are returned.

edited Sep 7, 2012 at 21:43

answered Aug 30, 2012 at 22:37

gabrtv

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2 Comments

William Pursell Over a year ago

This is probably the best approach, but the 22 chars at the end are to be kept, so v[-22:] is more appropriate

gabrtv Over a year ago

@WilliamPursell you're right, I misread the question. I've updated the answer accordingly.

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