awk: syntax for "if (array doesn't contain a particular index)" Post: 302703487

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Top Forums UNIX for Dummies Questions & Answers awk: syntax for "if (array doesn't contain a particular index)" Post 302703487 by agama on Wednesday 19th of September 2012 10:01:46 PM

09-19-2012

Registered User

You are getting the extra X at the end because you are executing your loop one time more than you have pairs in your string. This is the way I would have coded it:

Code:

awk '
    BEGIN {
        xtab["11"]="a";
        xtab["12"]="b";
        xtab["13"]="c";
    }
    function xlate( w,      xw, i, ss )
    {
        xw = "";
        for( i = 1; i < length( w ); i+= 2 )
        {
            ss = substr( w, i, 2 );
            xw = xw (ss in xtab ? xtab[ss] : "x");
        }

        return xw
    }
    { print xlate( $1 ); }
'

There isn't any bound checking to see that the word passed in is an even number of characters. You could also make the function accept both starting and ending positions in the word in addition to the word.

In my opinion, it's bad form to reference field values (e.g. $1) in a function. Better to pass in the contents of the field that you wish to operate on.

If you want to use a while loop (more cumbersome), then you'll need to 'look ahead' before looping. Something like this:

Code:

awk '
BEGIN {
        xtab["11"]="a";
        xtab["12"]="b";
        xtab["13"]="c";
    }
  
    # accepts word and starting offset 
    function xlate( w, start,       xw, n )
    {
        xw = ""
        n = substr(w, start, 2)    # seed n with first pair 
        while( n != "" )
        {
            xw = xw (n in xtab ? xtab[n] : "X")
            start = start + 2;
            n = substr(w, start, 2)    # look ahead to next; exit loop if at end
        }
        return xw
    }
    { print xlate($1, 1) }
'

Hope this gets you going again.

agama

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rpc.rquotad

RQUOTAD(8)						      System Manager's Manual							RQUOTAD(8)

NAME

       rpc.rquotad - remote quota server

SYNOPSIS

       /usr/sbin/rpc.rquotad [ -FI ] [ -p port ] [ -s | -S ] [ -x path ]

       /usr/sbin/rpc.rquotad [ -h | -V ]

DESCRIPTION

       rpc.rquotad  is	an  rpc(3) server which returns quotas for a user of a local filesystem which is mounted by a remote machine over the NFS.
       It also allows setting of quotas on NFS mounted filesystem (if configured during compilation and allowed by a command line option -S).  The
       results	are used by quota(1) to display user quotas for remote filesystems and by edquota(8) to set quotas on remote filesystems.  rquotad
       daemon uses tcp-wrappers library (under service name rquotad) which allows you to specify hosts allowed/disallowed to use the  daemon  (see
       hosts.allow(5) manpage for more information). The rquotad daemon is normally started at boot time from the system startup scripts.

OPTIONS

       -h, --help
	      Show program usage and exit.  -V, --version Show version of quota tools.

       -s, --no-setquota
	      Don't allow setting of quotas (default). This option is available only if utilities were compiled with the rpcsetquota option.

       -S, --setquota
	      Allow setting of quotas. This option is available only if utilities were compiled with the rpcsetquota option.

       -F, --foreground
	      Run daemon in foreground (may be useful for debugging purposes).

       -I, --autofs
	      Do not ignore autofs mountpoints.

       -p port, --port port
	      Listen on alternate port port.

       -x path, --xtab path
	      Set  an  alternative file with NFSD export table. This file is used to determine pseudoroot of NFSv4 exports. The pseudoroot is then
	      prepended to each relative path (i.e. a path not beginning by '/') received in a quota RPC request.

FILES

       aquota.user or aquota.group
			   quota file at the filesystem root (version 2 quota, non-XFS filesystems)
       quota.user or quota.group
			   quota file at the filesystem root (version 1 quota, non-XFS filesystems)
       /etc/mtab	   default filesystems

SEE ALSO

       quota(1), rpc(3), nfs(5), services(5), inetd(8)

																	RQUOTAD(8)