4 examples for for

  # Do stuff 10 times
for i in $(seq 10); do echo $i; done
        

  # loop over a list of files in bash
for f in file1 file2 file3
do
	echo "doing stuff to $f"
	# your commands here
done

# loop over all PDF files in the working directory
for f in *.pdf
do
	echo "doing stuff to $f"
	# your commands here
done

# do it in one line
for f in *.pdf; do command; done
        

  # Bash 3.0+ has ranges {start..end..incr} builtin:
for i in {1..10}; do echo $i; done
for i in {0..8..2}
        

  # WEB - Shows cookies, eTag and modules installed

for i in `cat 80.txt` ; do curl -iskXHEAD http://$i/ > $i 2>&1 ; echo Scanned $i ; done

# Find the IP address for every subdomain in list.txt.

for x in $(cat list.txt); do host $x | grep 'has address' | cut -d ' ' -f4; done

# DNS cache poisioning

for i in `53.txt`; do dig @"$i" +short porttest.dns-oarc.net TXT; done; > CachePoison.txt

# Non-recursive DNS queries

for i in `cat 53.txt`; do dig @"$i" www.google.com A +norecurse; done > NonRecurive.txt