Make interactive execute whenever possible

Here the trick is to restore those file descriptors (0, 1, 2) that have been
redirected (`dup2`) by the parent process.

First we need to determine which one has been redirected, for example by looking
at `ls -l /proc/$$/fd/`. Then we can use `0<&x`, `1>&x` or `2>&x` to restore 0,
1 or 2 respectively, where `x` is any file descriptor number that points to the
TTY.

It may happen that no file descriptor is unchanged, in that case we can use
`tty` to perform the redirection: sh <$(tty) >$(tty) 2>$(tty)

_gtfobins/sed.md

@@ -2,14 +2,14 @@
 functions:
   execute-interactive:
     - description: GNU version only. Also, this requires `bash`.
-      code: sed -n "1e bash -c 'exec 10<&0 11>&1 0<&2 1>&2; /bin/sh -i'" /etc/hosts
+      code: sed -n '1e exec sh 1>&0' /etc/hosts
   execute-non-interactive:
     - description: GNU version only.
       code: sed -n "1e id" /etc/hosts
   file-write:
     - code: |
         LFILE=file_to_write
-        sed -n "1s/.*/DATA/w $LFILE" /etc/hosts
+        sed -n '1e exec sh 1>&0 /etc/hosts
   file-read:
     - code: |
         LFILE=file_to_read
@@ -20,5 +20,5 @@ functions:
         ./sed -e '' "$LFILE"
   sudo-enabled:
     - description: GNU version only. Also, this requires `bash`.
-      code: sudo sed -n "1e /bin/bash -c 'exec 10<&0 11>&1 0<&2 1>&2; /bin/sh -i'" /etc/hosts
+      code: sudo sed -n '1e exec sh 1>&0 /etc/hosts
 ---