hmm, now what can I do with this...?

[pm215]

There's an interesting new feature in GNU sed 4.0:

   echo "yow" | sed -re 'y!why!man!;sv^vuv;yioiai;ss$se -asme;sg g\ngg'

So how many people knew you can now ask sed to execute an arbitrary shell command? Lots of possibilities for shell script nargery there. On the downside, I suppose we're going to have to start looking very carefully at sed commands before running them :-/ (I was going to suggest that we could use --posix to turn off the GNU extensions, but it doesn't actually seem to work! In any case there's a new sed command to say 'turn the GNU extensions on again'...)

Comments

[pm215]

Actually, you're right: (v is a version-check and enable-extensions command)

  zircon$ echo foo|sed --posix -e 'v'
  sed: -e expression #1, char 1: unknown command: `v'

so the main problem is that sed doesn't seem to be disabling e in POSIX mode:

   zircon$ echo foo|sed --posix -e 'e'
   sh: line 1: foo: command not found