Bash Process Substitution

I saw this and definitely wanted to share it.

diff two variables

Terminal window
VAR1="hello"
VAR2="helllo"
diff -u <(echo "$VAR1") <(echo "$VAR2")


# output:
--- /dev/fd/11  2026-01-17 20:03:59
+++ /dev/fd/12  2026-01-17 20:03:59
@@ -1 +1 @@
-hello
+helllo
Terminal window
paste <(seq 1 5) <(seq 6 10)


# output:
1  6
2  7
3  8
4  9
5  10

read in temp file

Terminal window
less < <(curl -s https://raw.githubusercontent.com/asdf8601/asdfff.dev/main/README.md)

redirect output to a process

Terminal window
echo "hello world" > >(tr a-z A-Z)


# output:
HELLO WORLD