Linux repeat string n times in command line

Method 1 : Use command Yes

j@ubuntu2004:~$ yes FOO | head -5 
FOO
FOO
FOO
FOO
FOO
j@ubuntu2004:~$ yes FOO | head -5  | xargs
FOO FOO FOO FOO FOO
j@ubuntu2004:~$

yes - output a string repeatedly until killed

xargs - replace new line with space

Method 2: use printf the print n space then replace the with your word

j@ubuntu2004:~$ printf "%5s" |sed 's/ /FOO /g'
FOO FOO FOO FOO FOO j@ubuntu2004:~$ 
j@ubuntu2004:~$ n=4
j@ubuntu2004:~$ printf "%${n}s" |sed 's/ /FOO /g'
FOO FOO FOO FOO j@ubuntu2004:~$

Method 3: Use command “seq” then replace the numbers with your foo

j@ubuntu2004:~$ seq 5
1
2
3
4
5
j@ubuntu2004:~$ seq 5 | sed "c FOO"
FOO
FOO
FOO
FOO
FOO
j@ubuntu2004:~$ seq 5 | sed "c FOO" | xargs
FOO FOO FOO FOO FOO
j@ubuntu2004:~$
j@ubuntu2004:~$ seq 5 | xargs  -I -- echo "FOO"
FOO
FOO
FOO
FOO
FOO

Method 4: Use for loop

j@ubuntu2004:~$ for i in {1..4}; do echo FOO;done
FOO
FOO
FOO
FOO
j@ubuntu2004:~$ for i in {1..4}; do echo -n "FOO ";done
FOO FOO FOO FOO j@ubuntu2004:~$

Note: For {1..4} there is no space