Is there a standard UNIX tool to repeat a command any number of times?

Solution 1:

Yes this is possible. Bash has a very extensive scripting language. In this case:

for i in {1..100}; do echo 'hello'; done

More looping examples: http://www.cyberciti.biz/faq/bash-for-loop/
Full bash reference: http://www.gnu.org/software/bash/manual/bashref.html

Solution 2:

The for loop syntax is silly. This is shorter:

seq 10|xargs -I INDEX echo "print this 10 times"

Solution 3:

Or would I write to do some kind of loop in bash?

Yes, you would, like this:

for(( i = 0; i < 100; i++ )); do echo "hello"; done

or, shorter:

for((i=100;i--;)); do echo "hello"; done

Solution 4:

In addition to more built in methods you could use an external utility that generates a sequence of numbers.

# gnu coreutils provides seq
for i in $(seq 1 100) ; do printf "hello\n" ; done

# freebsd (and probably other bsd) provides jot
for i in $(jot - 1 100) ; do printf "hello\n" ; done