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Full Discussion: Ensuring A String Doesn't Begin With Space
Top Forums Shell Programming and Scripting Ensuring A String Doesn't Begin With Space Post 302231786 by otheus on Wednesday 3rd of September 2008 06:42:33 AM
Old 09-03-2008
My God, Dennis, that's overkill.

Silentwolf, you're on the right track -- but the if statement won't work without double-quoting the space on the left-side. And then it won't work because the expansion of g_name results in a space gobbled up by the parser before finding its way to expr. Just prefix the expression with a character and get the 2nd character.

Code:
elif [ "`expr substr X$g_name 2 1`" = " " ] ; then
                                                echo "Given name may not begin with a space."

But I think there is a simpler way:

Code:
elif [ "`echo $g_name`" = "$g_name" ] ; then
                                                echo "Given name may not begin with a space."

HOWEVER, that will fail if the name contains MULTIPLE spaces or trails with a space (the echo command will seemingly "compress" each into one space and cut off the ending spaces).

Finally, if using ksh or bash, you can use the ${#%} operators, such as this:
Code:
elif [ " ${g_name# }" = "$g_name" ] ; then
                                                echo "Given name may not begin with a space."

This strips the leading space of g_name if it's there, then prefixes the space to g_name. If that is different than $g_name, it means the strip failed. There are other ways to do this, like:

Code:
elif [ "${g_name# }" != "$gname" ] ; then
                                                echo "Given name may not begin with a space."

OR

Code:
elif [ "${g_name%% *}" = "" ] ; then
                                                echo "Given name may not begin with a space."

Which is the reverse -- you cut everything after the space, including the space, and if the resulting string is empty, the cut succeeded and started with the first character of the string, ie, the first character was blank.
 

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gnunet-namestore

GNUNET-NAMESTORE(1)					      General Commands Manual					       GNUNET-NAMESTORE(1)

NAME

       gnunet-namestore - manipulate GNUnet zones

SYNOPSIS

       gnunet-namestore [options]-zZONEFILE

DESCRIPTION

       gnunet-namestore can be used to create and manipulate a GNS zone.

OPTIONS

       -a, --add
	      Desired operation is adding a record

       -c FILENAME,  --config=FILENAME
	      Use the configuration file FILENAME.

       -d, --delete
	      Desired operation is deleting a record

       -D, --display
	      Desired operation is listing of matching records

       -e TIME, --expiration=TIME
	      Specifies  expiration time of record to add; format is relative time, i.e "1 h" or "7 d 30 m".  Supported units are "ms", "s", "min"
	      or "minutes", "h" (hours), "d" (days) and "a" (years).

       -h, --help
	      Print short help on options.

       -L LOGLEVEL, --loglevel=LOGLEVEL
	      Use LOGLEVEL for logging.  Valid values are DEBUG, INFO, WARNING and ERROR.

       -n NAME, --name=NAME
	      Name of the record to add/delete/display

       -t TYPE, --type=TYPE
	      Type of the record to add/delete/display (i.e. "A", "AAAA", "NS", "PKEY", "MX" etc.)

       -v, --version
	      Print GNUnet version number.

       -V VALUE, --value=VALUE
	      Value to store or remove from the GNS zone.  Specific format depends on the record type.	A records expect  a  dotted  decimal  IPv4
	      address,	AAAA  records an IPv6 address, PKEY a public key in GNUnet's printable format, and CNAME and NS records should be a domain
	      name.

       -z FILENAME, --zonekey=FILENAME
	      Specifies the filename with the private key for the zone (mandatory option)

BUGS

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SEE ALSO

       gnunet-gns(1)

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