Diff to get changed line from second file - bash

I have two files file1 and file2. I want to print the new line added to file2 using diff.
file1
/root/a
/root/b
/root/c
/root/d
file2
/root/new
/root/new_new
/root/a
/root/b
/root/c
/root/d
Expected output
/root/new
/root/new_new
I looked into man page but there was no any info on this


If you don't need to preserve the order, you could use the comm command like:
comm -13 <(sort file1) <(sort file2)
comm compares 2 sorted files and will print 3 columns of output. First is the lines unique to file1, then lines unique to file2 then lines common to both. You can supress any columns, so we turn of 1 and 3 in this example with -13 so we will see only lines unique to the second file.
or you could use grep:
grep -wvFf file1 file2
Here we use -f to have grep get its patterns from file1. We then tell it to treat them as fixed strings with -F instead of as patterns, match whole words with -w, and print only lines with no matches with -v


Following awk may help you on same. This will tell you all those lines which are present in Input_file2 and not in Input_file1.
awk 'FNR==NR{a[$0];next} !($0 in a)' Input_file1 Input_file2


Try using a combination of diff and sed.
The raw diff output is:
$ diff file1 file2
0a1,2
> /root/new
> /root/new_new
Add sed to strip out everything but the lines beginning with ">":
$ diff file1 file2 | sed -n -e 's/^> //p'
/root/new
/root/new_new
This preserves the order. Note that it also assumes you are only adding lines to the second file.

Related

Finiding common lines for two files using bash

I am trying to compare two files and output a file which consists of common names for both.
File1
1990.A.BHT.s_fil 4.70
1991.H.BHT.s_fil 2.34
1992.O.BHT.s_fil 3.67
1993.C.BHT.s_fil -1.50
1994.I.BHT.s_fil -3.29
1995.K.BHT.s_fil -4.01
File2
1990.A.BHT_ScS.dat 1537 -2.21
1993.C.BHT_ScS.dat 1494 1.13
1994.I.BHT_ScS.dat 1545 0.15
1995.K.BHT_ScS.dat 1624 1.15
I want to compare the first parts of the names ** (ex:1990.A.BHT ) ** on both files and output a file which has common names with the values on 2nd column in file1 to file3
ex: file3 (output)
1990.A.BHT.s_fil 4.70
1993.C.BHT.s_fil -1.50
1994.I.BHT.s_fil -3.29
1995.K.BHT.s_fil -4.01
I used following codes which uses grep command
while read line
do
grep $line file1 >> file3
done < file2
and
grep -wf file1 file2 > file3
I sort the files before using this script.
But I get an empty file3. Can someone help me with this please?

You need to remove everything starting from _SCS.dat from the lines in file2. Then you can use that as a pattern to match lines in file1.
grep -F -f <(sed 's/_SCS\.dat.*//' file2) file1 > file3
The -F option matches fixed strings rather than treating them as regular expressions.

In your example data, the lines appear to be in sorted order. If you can guarantee that they always are, comm -1 -2 file1 file2 would do the job. If they can be unsorted, do a
comm -1 -2 <(sort file1) <(sort file2)

Difference between two files without sorting

I have the files file1 and file2, where file2 is a subset of file1. That means, if I iterate over file1, there are some lines that are in file2, and some that aren't, but there is no line in file2 that is not in file1. There may be several lines with the same content in a file. Now I want to get the difference between them, that is, all lines of file1 that aren't in file2.
According to this well received answer
diff(1) isn't the answer, comm(1) is.
(For whatever reason)
But as I understand, for comm the files need to be sorted first. The problem: Both files are ordered (not sorted!), and this order needs to be kept. So what I really want is to iterate over file1, and check for every line, if it is also in file2. If not, write it to file3. If the same content occurs more than once, it should be kept more than once!
Is there any way to do this with the command line?

Try this with GNU grep:
grep -vFf file2 file1 > file3
Update:
grep -vxFf file2 file1 > file3

I think you do not want to sort for avoiding temp files. This is possible with process substitution:
diff <(sort file1) <(sort file2)
# or
comm <(sort file1) <(sort file2)
Edit: Using https://stackoverflow.com/a/4544925/3220113 I found another alternative (for text files with short lines):
diff -a --suppress-common-lines -y file2 file1 | sed 's/\s*>.//'

Using cut and grep commands in unix

I have a file (file1.txt) with text as:
aaa,,,,,
aaa,10001781,,,,
aaa,10001782,,,,
bbb,10001783,,,,
My file2 contents are:
11111111
10001781
11111222
I need to search second field of file1 in file2 and delete the line from file1 if pattern is matching.So output will be:
aaa,,,,,
aaa,10001782,,,,
bbb,10001783,,,,
Can I use grep and cut commands for this?

This prints lines from file1.txt only if the second field is not in file2:
$ awk -F, 'FNR==NR{a[$1]=1; next;} !a[$2]' file2 file1.txt
aaa,,,,,
aaa,10001782,,,,
bbb,10001783,,,,
How it works
This works by reading file2 and keeping track of all lines seen in an associative array a. Then, lines in file1.txt are printed only if its column 2 is not in a. In more detail:
FNR==NR{a[$1]=1; next;}
When reading file2, set a[$1] to 1 to signal that we have seen the value on this line. We then instruct awk to skip the rest of the commands and start over on the next line.
This section is only run for file2 because file2 is listed first on the command line and FNR==NR only when we are reading the first file listed on the command line. This is because FNR is the number of lines read from the current file and NR is the total number of lines read so far. These two are equal only for the first file.
!a[$2]
When reading file1.txt, a[$2] evaluates to true if column 2 was seen in file2. Since ! is negation, !a[$2] evaluates to true when column 2 was not seen. When this evaluates to true, the line is printed.
Alternative
This is the same logic, expressed in a slightly different style, as suggested in the comments by Tom Fenech:
$ awk -F, 'FNR==NR{a[$1]; next;} !($2 in a)' file2 file1.txt
aaa,,,,,
aaa,10001782,,,,
bbb,10001783,,,,

Soulution with grep
$ grep -vf file2 file1.txt
aaa,,,,,
aaa,10001782,,,,
bbb,10001783,,,,
John1024's awk soulution would be faster for large files though.

bash delete lines in file containing lines from another file

file1 contains:
someword0
someword2
someword4
someword6
someword8
someword9
someword1
file2 contains:
someword2
someword3
someword4
someword5
someword7
someword11
someword1
So I wan't to have only lines from file1 which file2 doesn't contains. How can I do this in bash ?
That's the answer:
grep -v -x -f file2 file1
-v for select non-matching lines
-x for matching whole lines only
-f f2 to get patterns from f2.

You can use grep -vf:
grep -vwFf file2 file1
someword0
someword6
someword8
someword9
Check man grep for detailed info on all the grep options used here.

You could use the comm command as well:
comm -23 file1 file2
Explanation:
comm compares two files and prints, in 3 columns, lines unique to file1, file2, and lines in both.
Using the options -2 and -3 (or simply -23) suppresses printing of these columns, so you just get the lines unique to file1.

If your lines are unique, do a left join and filter out lines that exist in both tables.
join <(sort file1) <(sort file2) -o0,2.1 -a1 | awk '!$2'

Compare file1 and file2 but show only new lines which are not in file2

I am currently struggling with the task to compare two files. Both files have values which have differences and new lines. Example:
file1:
Germany=Munich
Swiss=Bern
Austria=Wien
Italy=Rom
file2:
Germany=Berlin
Swiss=Bern
Italy=Rom
The result of my action should be the following:
outputfile:
Austria=Wien
How can I achieve to get only lines to my output file which are not already in file2? I am not interested in differences of lines. Just a complete line which is missing.
I already experimented with diff and sdiff but without the desired results.
thanks

This should work:
awk -F= 'NR==FNR{a[$1]=$0;next}!($1 in a)' file2 file1
Austria=Wien
We read entire file2 first indexed at countries. We check if the country is not present in our file1 and print it. This won't give you results of lines which are in file2 but not in file1, but can be adjusted to give you that as well. I am not sure if that is your requirement. If it is then please update your question to reflect all your use-cases for more complete answer.

If you don't care about ordering, you can sort the files and then use join:
sort file1 > file1.srt
sort file2 > file2.srt
join -t'=' -v1 file1.srt file2.srt
The flags for join specify to use the equals sign as the field separator, include unpairable lines from file1.srt while suppressing the pairable lines from file1.srt.

This might work for you (GNU sed):
sed -r 's#([^=]*=).*#/^\1/d#' file2 | sed -f - file1
Use file2 as the basis for a sed script and run this sed script against file1

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