Search code examples
linuxshellprintfzsh

printf - Print n and then print a character n times in the next line

I have a variable n, which is a number, and I'm trying to produce an output like below for n=10:

10
1 1 1 1 1 1 1 1 1 1

So the first line is n, and the second line consists of n characters, in this example 1.

I know I can produce the second line with a command line this:

$ n=10
$ printf '1 %.0s' {1..$n}
1 1 1 1 1 1 1 1 1 1 %

So I can get the output I want with this series of commands:

$ n=10
$ printf "$n\n"; printf '1 %.0s' {1..$n}; printf '\n'
10
1 1 1 1 1 1 1 1 1 1

But I don't know how I can combine these commands into one printf command. The reason for emphasis on being one command is that I'm trying to redirect this output to another command for processing.

I was gonna ask the question on Unix Stackexchange, but I saw in the manual of printf that it works the same as the one in C, so I figured here I might get better results.

FORMAT controls the output as in C printf.

Solution

  • Use {} to group all the commands so you can redirect them all to the next command.

    { printf "$n\n"; printf '1 %.0s' {1..$n}; printf '\n'; } | some_other_command