Bash – How to Force Newlines with Cat Wildcard Printing

Perhaps you could do something like the following script (untested):

#!/bin/sh

for fn in "$@"; do
    source-highlight --out-format=esc -o STDOUT -i $fn 2>/dev/null || /bin/cat $fn
done

This does a few things:

• iterates through each command line argument
• tries to run source-highlight, redirecting error output to /dev/null
• if source-highlight fails, then run regular /bin/cat

You put this script in a file named cdc for example, then alias cat=cdc.

As a function

You can adapt the above script into a Bash function call which can then be incorporated into your dot files like so:

cdc() { 
  for fn in "$@"; do 
    source-highlight --out-format=esc -o STDOUT -i $fn 2>/dev/null || /bin/cat $fn;
  done 
}

Edit (Michael) for some reason trying to use ccat for the function name didn't work but cdc did!

The < isn't directly an aspect of bash command substitution. It is a redirection operator (like a pipe), which some shells allow without a command (POSIX does not specify this behavior).

Perhaps it would be more clear with more spaces:

echo $( < $FILE )

this is effectively* the same as the more POSIX-safe

echo $( cat $FILE )

... which is also effectively*

echo $( cat < $FILE )

Let's start with that last version. This runs cat with no arguments, which means it will read from standard input. $FILE is redirected into standard input due to the <, so cat puts its contents are put into standard output. The $(command) subsitution then pushes cat's output into arguments for echo.

In bash (but not in the POSIX standard), you can use < without a command. bash (and zsh and ksh but not dash) will interpret that as if cat <, though without invoking a new subprocess. As this is native to the shell, it is faster than literally running the external command cat. *This is why I say "effectively the same as."