Compare 20 files with diff, not 2

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Background

We are moving from managing hosts by hand to configuration management.

20 files

I want to compare 20 times a config file from 20 hosts. For example /etc/crontab

Use case

I guess about 15 of 20 files are identical. I want to see the five files which where modified with “vi” by hand.

I want an overview, no automated action like patching …

How to compare them …?

I tried my favorit diff tool (meld), but it does not allow more than three files 🙁

Answer

I try to wrap my head around what diffing 20 files to each other would accomplish, but maybe I have another approach.

I assume that you want to know what kind of cron jobs are defined over all of your systems. Instead of diffing the files, I propose to output them together, sort the output and then use uniq to omit duplicate lines:

File1: 

10 10 * * * /myjob.sh
* * * * * /everyminute.sh

File2: 

20 20 * * * /evening-job.sh
* * * * * /everyminute.sh

All jobs over all files: 

cat File1 File2  | sort | uniq -c

  1     10 10 * * * /myjob.sh
  1     20 20 * * * /evening-job.sh
  2     * * * * * /everyminute.sh

The first column shows the numer of times this job was defined.

Attribution
Source : Link , Question Author : guettli , Answer Author : Sven

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