Source code in the unix programming language

#!/bin/sh
# A leading hash symbol begins a comment.
echo "Hello"      # Comments can appear after a statement.

# The hash symbol must be at the beginning of a word.
echo This_Is#Not_A_Comment
#Comment

#!/bin/csh -f

# C Shell has a similar comment syntax, but only allows comments in a
# script file, not in terminal input.

echo Hello#With C Shell, the hash can also be in the middle of a word.

# Comments in es (extensible shell) look like those of other shells.

echo Hello#With es, the hash can also be in the middle of a word.