topic Re: sed Issue .. (delimiter) in Operating System - HP-UX

Sed Issue ..

rleon — Fri, 14 Sep 2012 15:40:00 GMT

I everyone I need some help with a sed statement.

This is a scirpt that updates the /etc/shadow on linux and solaris.

And I am having probems with one line.

ssh -q ${HOST} 2>/dev/null "rm /tmp/shadow.*"
ssh -q ${HOST} 2>/dev/null "cp /etc/shadow /tmp/shadow.bak"

ssh -q ${HOST} 2>/dev/null "sed -e '/^root:/s/:[^:]*:/:${PASS}:/' /tmp/shadow.bak > /tmp/shadow.new"

Most of the time it works without any issues but for some reason everyone once in a while /tmp/shadow.new is empty. The file is there .. just nothing in it.

-rw------- 1 root root 0 Sep 14 10:32 /tmp/shadow.new

Is there something wrong with my sed staement?

Or am I missing something?

Thanks

Ricardo

Re: Sed Issue ..

rleon — Fri, 14 Sep 2012 18:25:33 GMT

Im a little closer ..

it seems that the issue happens when the password hash has a \ or / in it.

I get the following errors:

sed: command garbled:

sed: -e expression #1, char 29: Unknown option to `s'

Re: sed Issue .. (delimiter)

Dennis Handly — Fri, 14 Sep 2012 20:10:14 GMT

>it seems that the issue happens when the password hash has a \ or / in it

You could replace that sed "/" by a comma.

Re: Sed Issue ..

rleon — Fri, 14 Sep 2012 19:26:08 GMT

Hi Dennis

Can you clarify ..

If the password hash is

abcdef123/ABC

And I change it to

abcdef123,ABC

That makes the password different and doesnt work.

Re: sed Issue .. (delimiter)

Dennis Handly — Fri, 14 Sep 2012 20:10:31 GMT

>Can you clarify?

Change your sed command to use "," as the delimiter:

ssh -q ${HOST} 2> /dev/null "sed -e '/^root:/s,:[^:]*:,:${PASS}:,' /tmp/shadow.bak > /tmp/shadow.new"

Re: sed Issue .. (delimiter)

rleon — Fri, 14 Sep 2012 20:21:08 GMT

Thanks !!!

That worked like a charm !!

Woud you mind explaining what the comma does?

Re: sed Issue .. (delimiter)

Dennis Handly — Sat, 15 Sep 2012 01:44:40 GMT

>Would you mind explaining what the comma does?

The same as the "/". :-)

You can use any char as the delimiter, as long as it matches. From sed(1):

      (2)s/regular expression/replacement/flags
                  Substitute replacement string for instances of regular
                  expression in the pattern space. Any character can be
                  used instead of /. For a fuller description see ed(1).

It seems you can even use a ";", though it is normally a command separator.