$ echo "abcdef" > sample1.txt $ cat sample1.txt abcdef
$ sed s/abc/def/ < sample1.txt > sample2.txt
$ cat sample2.txt defdef
$ ls perl/ sample.txt sample1.txt sample2.txt $ ls | sed 's/[a-z]/x/g'
xxxx/ xxxxxx.xxx xxxxxx1.xxx xxxxxx2.xxx
$ cat sample1.txt | sed 's/abc/ABC/'
ABCdef
$ cat sample.txt | sed 's/\([ab]\).\([def]\)/\1X\2/g'
abXdef
$ perl -pe 's/abc/def/g' < sample1.txt
defdef
