How to compare the 1st column of two files and if the strings match then print “true” [duplicate]

Question

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• To compare column1 of two files 1 answer

I have two files, say file1 and file2.

file1:

91 | 2018-10-11 16:07:14 | bkwdv | 188.0000 |
77 | 2018-10-12 15:05:15 | wvwef | 94.0000  | 

file2:

77 | 2018-10-12 15:05:15 | wvwef | 94.0000  
91 | 2018-10-11 16:07:14 | bkwdv | 188.0000 

I would like to compare the first column of file1 with the first column of file2.

In case the strings match (irrespective of the order, as in the given input data), it should print "success", else "exit". So, as per the given input data, it should print "success".

Please note that the number of rows in the first column could vary in either of the files, so in this case, it should exit.

Answer 1

Similar to my answer for your question here

#!/bin/bash
var=$(cut -d"|" -f 1 file  | sort -k1.1n)
var1=$(cut -d"|" -f 1 file | sort -k1.1n)

if [ "$var" == "$var1" ]
then
  echo "success"
else
  exit
fi

Explanation💡:

The delimiter -d in the command cut is set to a | with -d |, so cut can see the borders between the columns which are |. Then cut can pull out the fields of interest in column #1 with the -f flag.

In this example, we want the command sort to compare a limited subset of the data (i.e. data in column #1). For so, we specified which fields to compare using a key called the -k option. k1.1 will sort the first field, and ignore the rest columns. In other words, sort on column #1 to column #1 (i.e. sort only column #1).

According to sort man

-k, --key=POS1[,POS2]   Where POS1 is the starting field position, and POS2 is the ending field position

Answer 2

Extract column one from each file, sort them numerically, and compare them:

awk '{ print $1 }' <file1 | sort -n >file1.col1
awk '{ print $1 }' <file2 | sort -n >file2.col1

if cmp -s file1.col1 file2.col1; then
    echo 'success'
else
    echo 'exit'
fi

rm file1.col1 file2.col1

Or, using bash-specific syntax:

if cmp -s <( awk '{ print $1 }' <file1 | sort -n ) \
          <( awk '{ print $1 }' <file2 | sort -n )
then
    echo 'success'
else
    echo 'exit'
fi

The cmp -s command will not output anything but will exit successfully if its two file operands have identical contents. We use this in an if statement to figure out whether the sorted 1st columns of the two files are identical or not.

awk '{ print $1 }' in the code above could also be replaced by cut -d ' ' -f 1 if the whitespace character after the number in the first column is a space character.

Answer 3

You could check for unpairable lines in the sorted files using join, and test whether the result is the empty string:

[[ -z "$(join -t '|' -v1 -v2 <(sort file1) <(sort file2))" ]] && echo "success" || echo "exit"

Answer 4

Well in such conditions

1. cat both files
2. sort -n uniqe
3. count numer of result lines

If you got the sam number as the number of lines in both files, you got succes.

N1=$(cat file1 |wc -l) ;N2=$(cat file2 |wc -l); N3=$(cat file1 file2 |sort -nu |wc -l); echo $N1 $N2 $N3

If you need to get result: success / exit , you must compare the N1, N2, N3 yourself. Of course, it is recomended to compare N1 and N2 before you start to gether the result N3, and if equals, and you continue, then you compare only N1 with N3 (because you start count the N3 and thats why N1==N2).