Ubuntu – How to compare two files

command linetext processing

So basically what I want to do is compare two file by line by column 2. How could I accomplish this?

File_1.txt:

User1 US
User2 US
User3 US

File_2.txt:

User1 US
User2 US
User3 NG

Output_File:

User3 has changed

Best Answer

Look into the diff command. It's a good tool, and you can read all about it by typing man diff into your terminal.

The command you'll want to do is diff File_1.txt File_2.txt which will output the difference between the two and should look something like this:

enter image description here

A quick note on reading the output from the third command: The 'arrows' (< and >) refer to what the value of the line is in the left file (<) vs the right file (>), with the left file being the one you entered first on the command line, in this case File_1.txt

Additionally you might notice the 4th command is diff ... | tee Output_File this pipes the results from diff into a tee, which then puts that output into a file, so that you can save it for later if you don't want to view it all on the console right that second.

Related Solutions

Ubuntu – How to run a script when a directory is changed by another user

Using inoticoming:

You can put a script in /etc/init.d/ that runs inoticoming at boot time.

Create a new folder to hold the inoticoming log / last pid for the watched folder: sudo mkdir -p /var/log/inoticoming/watched/
Create a script inoticoming_watched in /etc/init.d/:

_{* Remember to change <path_to_folder> and <path_to_script> to match the full path of the watched folder and the full path of the script to execute}

#!/bin/sh

case "${1}" in
    start)
        inoticoming --logfile '/var/log/inoticoming/watched/inoticoming.log' --pid-file '/var/log/inoticoming/watched/inoticoming_last_pid.txt' <path_to_folder> <path_to_script> \;
    ;;

    stop)
        kill -15 $(< /var/log/inoticoming/watched/inoticoming_last_pid.txt tee)
    ;;

    restart)
        ${0} stop
        sleep 1
        ${0} start
    ;;

    *)
    echo "Usage: ${0} {start|stop|restart}"
    exit 1
    ;;
esac

Mark the script as executable: sudo chmod u+x /etc/init.d/inoticoming_watched
Make sure that the script called by inoticoming_watched is executable.
Update rc.d to make the service inoticoming_watched start at boot time: sudo update-rc.d inoticoming_watched defaults

You can check the inoticoming log in /var/log/inoticoming/watched.

Ubuntu – Awk – compare 2 files and print columns from both files

If you have GNU awk (available from the repository via package gawk), which supports multi-dimensional arrays, you could do

gawk 'NR==FNR {a[$1][$2]++; next} $1 in a {for (x in a[$1]) print $0, x}' OFS="\t" file_2.txt file_1.txt

Ex.

$ gawk 'NR==FNR {a[$1][$2]++; next} $1 in a {for (x in a[$1]) print $0, x}' OFS="\t" file_2.txt file_1.txt
apple   2.5     5       7.2     :::N
great   3.8     10      3.6     :::ADJ
see     7.6     3       4.9     :::V
tree    5.4     11      5       :::N
back    8.9     2       2.1     :::ADJ
back    8.9     2       2.1     :::N

Otherwise, if output order is not important the easiest solution is probably to use the join command instead:

$ join -t $'\t' <(sort file_1.txt) <(sort file_2.txt)
apple   2.5     5       7.2     :::N
back    8.9     2       2.1     :::ADJ
back    8.9     2       2.1     :::N
great   3.8     10      3.6     :::ADJ
see     7.6     3       4.9     :::V
tree    5.4     11      5       :::N

Best Answer

Related Solutions

Ubuntu – How to run a script when a directory is changed by another user

Ubuntu – Awk – compare 2 files and print columns from both files

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