[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Help-bash] How to extrapolate bash string?

From: Eric Blake
Subject: Re: [Help-bash] How to extrapolate bash string?
Date: Thu, 12 Sep 2013 13:05:59 -0600
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130805 Thunderbird/17.0.8

On 09/11/2013 10:22 PM, Chris Down wrote:
> On 2013-09-11 22:30, Peng Yu wrote:
>> This message does not seem to provide a solution. If 'eval' is not
>> used, what else can be used?
> It's a thread, I'm not referring to that individual message.

In particular, mentions:

case $1 in
  \~ )
    printf '%s\n' "$HOME" ;;
  \~/* )
    printf '%s\n' "$HOME/${1#??}" ;;
  \~* )
    # Sanitize user before feeding it to eval.
    # You must adjust this code based on what characters are legal in your
    # system's usernames.  If your system allows shell metacharacters in
    # usernames, you are screwed.  Just give up now (switch to perl).
    if [[ $user != "$user2" ]]; then
      echo "Error: invalid characters in username" >&2
      exit 1
    eval "home=~$user2"
    case $1 in
      */* ) printf '%s\n' "$home/$path" ;;
      *   ) printf '%s\n' "$home" ;;
    esac ;;
  * )
    printf '%s\n' "$1" ;;

and followups pointed out that instead of erroring out for shell
metacharacters, that it should just print them as-is (after all, the
only way to combine ~ and a metacharacter into a single word is to use
quoting, but quoting disables tilde-expansion).

Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library

Attachment: signature.asc
Description: OpenPGP digital signature

reply via email to

[Prev in Thread] Current Thread [Next in Thread]