Select Code to Download

for Unix:
 perl -i.bak -0777 -lpe 's/\nef\n/\nef\na test content\n<blank line>\n
+/' a.txt

for Windows:
 perl -i.bak -0777 -lpe "s/\nef\n/\nef\na test content\n<blank line>\n
+/" a.txt

Unix:
 perl -i.bak -pe 'print "a test content\n<blank line>\n" if $.==4' a.t
+xt

Windows:
 perl -i.bak -pe "print qq{a test content\n<blank line>\n} if $.==4" a
+.txt