问题
How to count number of integers in a file using egrep?
I tried to solve it as a pattern finding problem. Actually, I am facing problem of how to represent range of characters [0-9] continuously which include "space" before the beginning and "space or dot" after the end. I think the latter can be solved by using \< and \> respectively. Also, It should not include dot in between otherwise it will not be an integer. I am unable to convert this logic into regular expression using available tools and techniques.
My name is 2322.
33 is my sister.
I am blessed with a son named 55.
Why are you so 69. Is everything 33.
66.88 is not an integer
55whereareyou?
The right answer should be 5 i.e. for 2322, 33, 55, 69 and 33.
回答1:
grep -Eo '(^| )([0-9]+[\.\?\=\:]?( |$))+' | wc -w
^^ ^ ^ ^ ^ ^ ^
|| | | | | | |
E = extended regex--------+| | | | | | |
o = extract what found-----+ | | | | | |
starts with new line or space---+ | | | | |
digits--------------------------------+ | | | |
optional dot, question mark, etc.-------------+ | | |
ends with end line or space----------------------------+ | |
repeat 1 time or more (to detect integers like "123 456")--+ |
count words------------------------------------------------------+
Note: 123. 123? 123: are also counted as integer
Test:
#!/bin/bash
exec 3<<EOF
My name is 2322.
33 is my sister.
I am blessed with a son named 55.
Why are you so 69. Is everything 33.
66.88 is not an integer
55whereareyou?
two integers 123 456.
how many tables in room 400? 50.
50? oh I thought it was 40.
23: It's late, 23:00 already
EOF
grep -Eo '(^| )([0-9]+[\.\?\=\:]?( |$))+' <&3 | \
tee >(sleep 0.5; echo -n "integer counted: "; wc -w; )
Outputs:
2322.
33
55.
69.
33.
123 456.
400? 50.
50?
40.
23:
integer counted: 12
回答2:
Based on the observation that you want 66.88 excluded, I'm guessing
grep -Ec '[0-9]\.?( |$)' file
which finds a digit, optionally followed by a dot, followed by either a space or end of line.
The -c option says to report the number of lines which contain a match (so not strictly the number of matches, if there are lines which contain multiple matches) and the -E option enables extended regular expression syntax, i.e. what was traditionally calned egrep (though the command name is now obsolescent).
If you need to count matches, the -o option prints each match on a separate line, which you can then pass to wc -l (or in lucky cases combine with grep -c, but check first; this doesn't work e.g. with GNU grep currently).
回答3:
On my ubuntu this code working fine
grep -P '((^)|(\s+))[-+]?\d+\.?((\s+)|($))' test
来源：https://stackoverflow.com/questions/48358662/number-of-intergers-in-a-file-using-command-line-interface