In Bash, how do I repeat a series of commands with a word substitute

Question

What I'm looking for is something that would perform a series of commands like this:

# cat file1 >> concated_file
# cat file2 >> concated_file
# cat file3 >> concated_file
# cat file4 >> concated_file

But wouldn't require me to retype the whole command 3 additional times. Maybe just be able to replace the argument from the previous command with syntax like the following:

# cat file1 >> concated_file
# s/file1/file2
# s/file2/file3
# s/file3/file4

I know that if the last argument is the same you could do this:

# cp -p test1.txt test2.txt
# chmod 777 $_
# chown nimmylebby: $_

And you could also use Bash loops like so:

# for f in 'file1' 'file2'; 
> do 
> chmod 750 $f;
> done

However, the above 2 examples are not what I'm looking. I just want to perform a series of commands which only differ by one argument without using for loops. Is this possible? Might not be but hoping it is ;-).

Answer 1

• Press Up, edit the command as necessary, press Enter.

• As previously, but arrange for the changing word to come last in the command for easier edition, e.g., cat >> concated_file file1. This is straightforward with your example command, not so in all cases.

• Define a function taking the variable part as an argument: f () { cat "$1" >> concated_file; }. Then invoke the function several times: f file1, f file2, …

• Use history expansion. Here you can do ^file1^file2.

Answer 2

Maybe what you need is a function:

function mycat() { cat $1 >> concated_file; }
mycat file1
mycat file2
mycat file3
mycat file4