How to identify the number of column in a file just like Python enumerate?

Question

Sample file:

11:34:21.590434 IP 10.10.1.30 > 10.10.1.217: ICMP echo reply, id 27948, seq 1, length 64

In Python, it's easy to identify the number of field by using enumerate function. E.g.

>>> i = '11:34:21.590434 IP 10.10.1.30 > 10.10.1.217: ICMP echo reply, id 27948, seq 1, length 64'
>>>

Split the string

>>> i.split()
['11:34:21.590434', 'IP', '10.10.1.30', '>', '10.10.1.217:', 'ICMP', 'echo', 'reply,', 'id', '27948,', 'seq', '1,', 'length', '64']
>>>

Put it on new variable, let say j

>>> j = i.split()
>>>

Enumerate it

>>> for i in enumerate(j, 1): i
... 
(1, '11:34:21.590434')
(2, 'IP')
(3, '10.10.1.30')
(4, '>')
(5, '10.10.1.217:')
(6, 'ICMP')
(7, 'echo')
(8, 'reply,')
(9, 'id')
(10, '27948,')
(11, 'seq')
(12, '1,')
(13, 'length')
(14, '64')
>>>

So, if I want to print out the source IP which is field number 3 with awk, it's so easy rather than to identify it manually with naked eyes.

wolf@linux:~$ awk '{print $3}' file.txt 
10.10.1.30
wolf@linux:~$

I know it's possible to do similar thing in Linux/Bash, I just can't figure it out yet.

Update

I know it's easy to get the number of column by using NF

wolf@linux:~$ awk '{ print NF }' file.txt
14
wolf@linux:~$

But what I want to achieve here is to identify each column and it's numbers. Probably something similar like Python enumerate output.

Does this answer your question? Split words from `read` and store to array? — user451199
– user451199, Commented Jan 31, 2021 at 8:11

Stephen Kitt · Accepted Answer · 2021-01-31 08:38:40Z

1

You can enumerate the fields using AWK:

awk '{ for (i = 1; i <= NF; i++) print i, $i }' file.txt

or with tr and nl:

tr ' ' '\n' < file.txt | nl

(Filter through head -n1 first if you want to stop at the end of the first line with tr; otherwise fields will be counted across lines.)

You can also find this out using Bash arrays (depending on IFS):

arr=($(head -n1 file.txt))
i=0
while [[ i -lt ${#arr[@]} ]]; do
    printf "%d %s\n" $((i+1)) "${arr[$i]}"
    ((i++))
done

edited Jan 31, 2021 at 8:38

answered Jan 31, 2021 at 8:11

Stephen Kitt

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Ed Morton · Accepted Answer · 2021-01-31 15:38:48Z

1

With GNU awk for multi-char RS and \s shorthand for [[:space:]]:

$ awk -v RS='\\s+' '{print NR, $0}' file
1 11:34:21.590434
2 IP
3 10.10.1.30
4 >
5 10.10.1.217:
6 ICMP
7 echo
8 reply,
9 id
10 27948,
11 seq
12 1,
13 length
14 64

It assumes you only have 1 line in your input just like in the example in your question.

answered Jan 31, 2021 at 15:38

Ed Morton

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Thanks, but I did not get similar output ... wolf@linux:~$ awk -v RS='\\s+' '{print NR, $0}' file.txt 1 11:34:21.590434 IP 10.10.1.30 > 10.10.1.217: ICMP echo reply, id 27948, 2 eq 1, length 64 wolf@linux:~$ echo $SHELL /bin/bash wolf@linux:~$

Wolf
– Wolf

2021-01-31 17:03:33 +00:00
Commented Jan 31, 2021 at 17:03
Then you copy/pasted wrong, or you aren't using gawk as the answer says is required, or your input doesn't look like the line you posted. If you use the script I posted on the input you posted using gawk as I said is required then you WILL get the output I posted.

Ed Morton
– Ed Morton

2021-01-31 17:18:24 +00:00
Commented Jan 31, 2021 at 17:18

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Hossein Vatani · Accepted Answer · 2021-01-31 08:39:55Z

0

I guessed there are not any right solution rather than Stephen Kitt. but if you only need IP Addrerss you could use below

tr ' ' '\n' <<<'11:34:21.590434 IP 10.10.1.30 > 10.10.1.217: ICMP echo reply, id 27948, seq 1, length 64' | grep IP -A1 | grep -v IP

answered Jan 31, 2021 at 8:39

Hossein Vatani

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score 0 · Accepted Answer · 2021-01-31 08:48:37Z

0

Hope this helps

$ tr ' ' '\n' < file.txt | nl
     1  11:34:21.590434
     2  IP
     3  10.10.1.30
     4  >
     5  10.10.1.217:
     6  ICMP
     7  echo
     8  reply,
     9  id
    10  27948,
    11  seq
    12  1,
    13  length
    14  64
$

or

$ read -ab < file.txt 
$ for c in ${b[*]}; do echo $c; done | nl
     1  11:34:21.590434
     2  IP
     3  10.10.1.30
     4  >
     5  10.10.1.217:
     6  ICMP
     7  echo
     8  reply,
     9  id
    10  27948,
    11  seq
    12  1,
    13  length
    14  64
$

edited Jan 31, 2021 at 8:48

answered Jan 31, 2021 at 8:30

user436512

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user264359 · Accepted Answer · 2021-01-31 17:10:06Z

0

Solution with sed

$ sed -n '/1/{s/ /\n/g;p}' < file.txt | nl
     1  11:34:21.590434
     2  IP
     3  10.10.1.30
     4  >
     5  10.10.1.217:
     6  ICMP
     7  echo
     8  reply,
     9  id
    10  27948,
    11  seq
    12  1,
    13  length
    14  64
       
$

answered Jan 31, 2021 at 17:10

user264359

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Wolf · Accepted Answer · 2021-01-31 17:48:43Z

0

grep out the fields and lay them one per line. Then number them with grep's -n option.

echo "....." |
grep -Po  '\S+' | grep -n ^ | sed 's/:/ /'

or

cat file.txt | grep -Po  '\S+' | grep -n ^ | sed 's/:/ /'

For perls more recent than 5.14.4

perl -lane '
  while (my($i,$e) = each @F) { print "$i $e"; }
' file.input

edited Jan 31, 2021 at 17:48

Wolf

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answered Jan 31, 2021 at 12:03

guest_7

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