How to Diff Top Lines of Two Files Without Intermediate File

How to diff top lines of two files without intermediate file

You're probably thinking of process substitution in bash. For example, try:

 diff <(head -n 2000 file1.log) <(head -n 2000 file2.log)

How to execute diff on outputs of two scripts without creating temporary files?

You can use process substitution in bash to compare the outputs of two commands. For example, try:

 diff <(./p3 < 1.in) <(./p4 < 1.in)

(And for prettier output you could use colordiff instead of diff :))

Compare two text files line by line

String directory = @"C:\Whatever\";
String[] linesA = File.ReadAllLines(Path.Combine(directory, "FileA-Database.txt"));
String[] linesB = File.ReadAllLines(Path.Combine(directory, "FileB-Database.txt"));

IEnumerable<String> onlyB = linesB.Except(linesA);

File.WriteAllLines(Path.Combine(directory, "Result.txt"), onlyB);

How to extract lines based on a substring from two separate text files in python?

You can avoid all the complicated lookups if you create a simple key, value dict from the first file and then generate the output on the fly whilst reading the second file:

with open('TextFile_1.txt') as f1:
    lookup = dict([x.strip() for x in line.split(',')] for line in f1)

with open('Output.txt', 'w') as out:
    with open('TextFile_2.txt') as f2:
        for line in f2:
            k, v = [x.strip() for x in line.split(',')]
            n = lookup[k.split('_')[0]]
            out.write(', '.join(
                [k, v, n, 'same' if v == n else 'different']) + '\n')

Output:

K_1, 6, 6, same
K_2, 5, 6, different
J_1, 4, 5, different
J_2, 4, 5, different
J_3, 5, 5, same
L_1, 4, 4, same

Perl script to compare two files but print in order

This can be done efficiently in two steps. Let's assume you have been able to find the "lines that match" but they are in the wrong order; then a simple grep can re-organize them. Assuming you have a script matchThem that takes two inputs (file1 and file2) and outputs them to tempFile, then the over all script will be:

matchThem file1 file2 > tempFile
grep -Fx -f tempFile file1

The -Fx flag means:

-F : find exact match only (much faster than wildcards)
-x : only match whole lines

Bash: finding which lines have not changed between two files

You can use this awk command for that:

awk 'FNR==NR{a[FNR]=$0; next} a[FNR] == $0{print FNR}' file1 file2
2
5

Breakup of awk command:

NR == FNR {                  # While processing the first file
  a[FNR] = $0                # store the line by the line #
  next                       # move to next record
}
                             # while processing the second file
a[FNR] == $0                 # current record is same as array value 
                             # with index of current line #
print FNR                    # print record number

Visual Studio Code - is there a Compare feature like that plugin for Notepad ++?

You can compare files from the explorer either from the working files section or the folder section. You can also trigger the global compare action from the command palette.

1. Open a folder with the files you need to compare,
2. Select two using SHIFT
3. Right click "Compare Selected"
   

How to get the difference (only additions) between two files in linux

diff and then grep for the edit type you want.

diff -u A1 A2 | grep -E "^\+"

What is the best way to compare two directories in Windows 10?

You can use BeyondCompare the diff tool to compare the contents of different directories, but you need to install it first.

What is the Windows equivalent of the diff command?

Run this in the CMD shell or batch file:

FC file1 file2

FC can also be used to compare binary files:

FC /B file1 file2

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