Subject: bug#16618: How to show the diff command when there is a difference when comparing two files?

From: Peng Yu <[email-masked]>
Date: Sat, 1 Feb 2014 13:27:55 -0600

Hi,

The following shows that diff -r print the command e.g. "diff -r
/var/folders/ft/9trh7jt57kqc_hyq0wm5rny40000gx/T/tmp.wcrIdLELps/b.txt
/var/folders/ft/9trh7jt57kqc_hyq0wm5rny40000gx/T/tmp.AJieJ9Zk1O/b.txt"
if there is an error. I'm wondering if I just compare two files, it is
possible to print the diff command if there is a difference between
the two files? Thanks.

~/linux/test/gnu/diffutils/diff/-r$ cat main.sh
#!/usr/bin/env bash

dir1=$(mktemp -d)
dir2=$(mktemp -d)
echo 'Hello World' > "$dir1/a.txt"
echo 'Hello World' > "$dir2/a.txt"

echo 'Hello World' > "$dir1/b.txt"
echo 'Hello World!' > "$dir2/b.txt"

#echo 'Hello World' > "$dir1/c.txt"
echo 'Hello World' | gzip -n > "$dir1/c.txt.gz"
diff -r "$dir1" "$dir2"

~/linux/test/gnu/diffutils/diff/-r$ ./main.sh
diff -r /var/folders/ft/9trh7jt57kqc_hyq0wm5rny40000gx/T/tmp.wcrIdLELps/b.txt
/var/folders/ft/9trh7jt57kqc_hyq0wm5rny40000gx/T/tmp.AJieJ9Zk1O/b.txt
1c1
< Hello World
---
> Hello World!
Only in /var/folders/ft/9trh7jt57kqc_hyq0wm5rny40000gx/T/tmp.wcrIdLELps:
c.txt.gz

-- 
Regards,
Peng