bash - extracting lines that contain only 3 columns

Question

I have a file that include the following lines :

2 | blah | blah
1 | blah | blah
3 | blah
2 | blah | blah
1
1 | high | five
3 | five

I wanna extract only the lines that has 3 columns (3 fields, 2 seperators...)
I wanna pipe it to the following commands :

| sort -nbsk1 | cut -d "|" -f1 | uniq -d

So after all I will get only :

2
1

Any suggestions ? It's a part of homework assignment, we are not allowed to use awk\sed and some more commands.. (grep\tr and whats written above can be used)

Thanks

I tried checking it line by line instead of sorting it. Much less "friendly" then checking a sorted and a ready list — Nadav Peled, May 24 '13 at 10:55

Kent · Answer 1 · 2013-05-24T11:00:10.937

1

since you said grep is allowed:

grep -E '^([^|]*\|){2}[^|]*$' file

edited May 24 '13 at 11:00

answered May 24 '13 at 10:53

Kent

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@tarrsalah thx. for OP's requirement, I think `grep '|.*|' ` works too. – Kent May 24 '13 at 11:19

Salah Eddine Taouririt · Accepted Answer · 2013-05-24T11:10:51.727

0

grep '.*|.*|.*' will select lines with at least three fields and two separators.

edited May 24 '13 at 11:10

answered May 24 '13 at 11:00

Salah Eddine Taouririt

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but not `extract only the lines that has 3 columns` e.g. `a|b|c|d` will be matched too. it does it in greedy way. – Kent May 24 '13 at 11:02
yeah @Kent, I will try to improve it. – Salah Eddine Taouririt May 24 '13 at 11:03
We know for sure (we can assume it) that we'll have a maximum of 3 columns, so cannot have this situation. – Nadav Peled May 24 '13 at 11:04
1

@NadavPeled please write those stuff in your question next time. it is very important information. – Kent May 24 '13 at 11:06
@NadavPeled if so, I think my solution is what you need. – Salah Eddine Taouririt May 24 '13 at 11:08
Can it be piped before the sort so the sort will get only the lines with 3 columns ? – Nadav Peled May 24 '13 at 11:11
@NadavPeled yeah, try it yourself. – Salah Eddine Taouririt May 24 '13 at 11:11
Sorry for the bump, but we wrote it, it worked, and suddenly stopped working. Is this pipe correct ? done < $1 | `echo grep '.*|.*|.*'` | sort -nbsk1 | cut -d "|" -f1 | uniq -d – Nadav Peled May 24 '13 at 16:05

bash - extracting lines that contain only 3 columns

2 Answers2