在 ccc 後面加上一行 xxx
# cat test
aaa
bbb
ccc
ddd
# perl -pi -e "s/ccc/ccc\nxxx/" test
# cat test
aaa
bbb
ccc
xxx
ddd
把 xxx 換成 yyy
# perl -pi -e "s/xxx/yyy/" test
# cat test
aaa
bbb
ccc
yyy
ddd
把檔案中含有 xxx 字串的下一行加上一行 new line
# cat test
aaa 111
bbb 222
ccc 333
555 xxx 444
ddd kkkkkkkkkkkkk
xxx 666
mmmmmmmmmmmmm
lllllllllllllllllxxx
eeeeeee
# sed -e '/xxx/a\
new line' test > test.tmp
# mv test.tmp test
# cat test
aaa 111
bbb 222
ccc 333
555 xxx 444
new line
ddd kkkkkkkkkkkkk
xxx 666
new line
mmmmmmmmmmmmm
lllllllllllllllllxxx
new line
eeeeeee