Given two files, I want to write a shell script that reads each line from file1 and checks if it is there in file2. If a line is not found it should output two files are different and exit. The files can contain words numbers or anything. For example :
file1 :
Hi!
1234
5678
1111
hellofile2:
1111
5678
1234
Hi!
helloIn this case two files should be equal. if file2 has "hello!!!" instead of "hello" then the files are different. I'm using bash script. How can I do this. It is not important that I need to do it in a nested loop but that's what I thought is the only way. Thanks for your help.
5 Answers
In bash:
diff --brief <(sort file1) <(sort file2)diff sets its exit status to indicate if the files are the same or not. The exit status is accessible in the special variable $?. You can expand on Ignacio's answer this way:
diff --brief <(sort file1) <(sort file2) >/dev/null
comp_value=$?
if [ $comp_value -eq 1 ]
then echo "do something because they're different"
else echo "do something because they're identical"
fiShould also work :
comm -3 file1 file2I think this is enough characters for an answer...
Whilst diff is a perfectly fine answer, I'd probably use cmp instead which is specifically for doing a byte by byte comparison of two files.
Because of this, it has the added bonus of being able to compare binary files.
if cmp -s "file1" "file2"
then echo "The files match"
else echo "The files are different"
fiI'm led to believe it's faster than using diff although I've not personally tested that.
Adding this because I think the [[ ]] && || construct is pretty neat:
#!/bin/bash
[[ `diff ${HOME}/file1 ${HOME}/file2` ]] && (echo "files different") || (echo "files same")
