How do I use cut to separate by multiple whitespace?

Question

I have this input, which is displayed in columns. I would like to get the second last column with the numbers of this sample:

[  3]  1.0- 2.0 sec  1.00 MBytes  8.39 Mbits/sec
[  3]  2.0- 3.0 sec   768 KBytes  6.29 Mbits/sec
[  3]  3.0- 4.0 sec   512 KBytes  4.19 Mbits/sec
[  3]  4.0- 5.0 sec   256 KBytes  2.10 Mbits/sec
...

If I use

cut -d\  -f 13

I get

Mbits/sec
6.29
4.19
2.10

because sometimes there are additional spaces in between.

Answer 1

If we use tr command along with squeeze option (-s flag ) to convert all multiple consecutive spaces to a single space and then perform cut operation with space as delimiter – we can access the required column carrying the numbers:

< file tr -s ' ' | cut -d ' ' -f 8

Answer 2

To answer your question literally:

sed 's/   */:/g' | cut -d : -f 5

or

awk -F '  +' '{print $5}'

But that won't do if the number in brackets reaches 10, etc. If you're only interested in the numbers, you could remove everything else.

sed 's/[^.0-9][^.0-9]*/:/g' | cut -d : -f 6

Answer 3

These commands will all print the last column of a space separated file:

• awk '{print $NF}' file

  in awk, NF is the number of fields and $NF is the last field.

• perl -lane 'print $F[$#F]' file

  -a splits the file on whitespace into the array @F, $#F is the number of elements in the array so $F[$#F] is the last element. The -n means read the file given on the command line and apply the script passed with -e to each line. -l just adds a newline character (\n) to each print statement.

• sed 's/.* //g'

  a simple regular expression that matches everything to the last space and deletes it, leaving only the last column.

• rev file | cut -d' ' -f 1 | rev

  rev reverses its output so the last field is the first, cut with delimiter space to print it and rev to reverse the text back to normal. This won' t work if you have consecutive whitespace.

Based on your input, I am guessing you don't actually want the last column but the penultimate one or the two last ones. In that case use these to print the last 2 (8.39 Mbits/sec):

awk '{print $(NF-1),$NF}' file 
perl -lane 'print "$F[$#F-1] $F[$#F]"' file 
sed 's/.* \(.* .*\)/\1/' file 
rev file | cut -d' ' -f 1,2 | rev

and these to print the penultimate (8.39):

awk '{print $(NF-1)}' file 
perl -lane 'print $F[$#F-1]' file 
sed 's/.* \(.*\) .*/\1/' file 
rev file | cut -d' ' -f 2 | rev

Answer 4

You can't separate multiple occurrence of whitespaces using cut as per manual:

Output fields are separated by a single occurrence of the field delimiter character.

unless the text is separated by the same amount or you use tr to remove excess of them.

Otherwise use alternative tools such as awk, sed or ex.

For example:

ex -s +'%norm $2Bd0' +%p +q! foo.txt

Replace +q! with -cwq to save the changes in-place.

Answer 5

Use a perl one-liner like so:

perl -lane 'print $F[-2]' input_file

Explanation:

Option -e causes the perl interpreter to look for the script inline, rather than in a file.

Option -n causes the input (file or STDIN from a pipe) to be read line by line.

Option -l strips the input record separator (OS-dependent, newline on UNIX by default) after reading the line, and adds it at the end to every print

Option -a causes each input line to be split on whitespace into array @F, and $F[-2] is the second element counting from the end, which is the field you want. You can also use $F[$#F-1], where $#F is the last index of the array @F, which is slightly less readable.

Answer 6

the right option for columned input into cut would be

cut -c35-38

Answer 7

Use the -w option, if your cut version is BSD compatible

$ echo "firstColumn        secondColumn   thirdColumn" | cut -w -f3
thirdColumn

Answer 8

Answering the question in the body instead of the one in the heading:

echo '[  3]  2.0- 3.0 sec   768 KBytes  6.29 Mbits/sec' \
| rev | cut -d' ' -f1 | rev

Obviously use -f2 but the question asks for the last column so I comply.

Answer 9

Using Raku (formerly known as Perl_6)

raku -ne '.words[*-2..*].put;' 

Sample Input:

[  3]  1.0- 2.0 sec  1.00 MBytes  8.39 Mbits/sec
[  3]  2.0- 3.0 sec   768 KBytes  6.29 Mbits/sec
[  3]  3.0- 4.0 sec   512 KBytes  4.19 Mbits/sec
[  3]  4.0- 5.0 sec   256 KBytes  2.10 Mbits/sec

Sample Output:

8.39 Mbits/sec
6.29 Mbits/sec
4.19 Mbits/sec
2.10 Mbits/sec

You might want to try Raku, a member of the Perl-family of programming languages. Above, the words routine breaks on whitespace. Columns can be selected with square brackets: since Raku (and Perl) are zero-indexed, the second-to-last column is *-2 and the last column is *-1. Here, either words[*-2..*-1] or words[*-2..*] works, the latter indicating 'give me the second-to-last column up to * whatever'.

Oh, the OP only wants the second-to-last column? Titled by the last column?

~$ raku -ne '.words[*-1].put if ++$ == 1; .words[*-2].put;' file
Mbits/sec
8.39
6.29
4.19
2.10

https://docs.raku.org/routine/words
https://raku.org

Answer 10

I've created a patch that adds new -m command-line option to cut, which works in the field mode and treats multiple consecutive delimiters as a single delimiter. This basically solves the OP's question in a rather efficient way. I also submitted this patch upstream a couple of days ago, and let's hope that it will be merged into the coreutils project.

There are some further thoughts about adding even more whitespace-related features to cut, and having some feedback about all that would be great. I'm willing to implement more patches for cut and submit them upstream, which would make this utility more versatile and more usable in various real-world scenarios.