10-09-2008
try -n
if [ -n "$yourvariable" ]
It may be Grep returns a space in that case it may not be Zero length .. try -n
-z
string is "null", that is, has zero length
-n
string is not "null".
Caution
The -n test absolutely requires that the string be quoted within the test brackets. Using an unquoted string with ! -z, or even just the unquoted string alone within test brackets (see Example 7-6) normally works, however, this is an unsafe practice. Always quote a tested string.
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shift(1) User Commands shift(1)
NAME
shift - shell built-in function to traverse either a shell's argument list or a list of field-separated words
SYNOPSIS
sh
shift [n]
csh
shift [variable]
ksh
* shift [n]
DESCRIPTION
sh
The positional parameters from $n+1 ... are renamed $1 ... . If n is not given, it is assumed to be 1.
csh
The components of argv, or variable, if supplied, are shifted to the left, discarding the first component. It is an error for the variable
not to be set or to have a null value.
ksh
The positional parameters from $n+1 $n+1 ... are renamed $1 ..., default n is 1. The parameter n can be any arithmetic expression that
evaluates to a non-negative number less than or equal to $#.
On this man page, ksh(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways:
1. Variable assignment lists preceding the command remain in effect when the command completes.
2. I/O redirections are processed after variable assignments.
3. Errors cause a script that contains them to abort.
4. Words, following a command preceded by ** that are in the format of a variable assignment, are expanded with the same rules as a vari-
able assignment. This means that tilde substitution is performed after the = sign and word splitting and file name generation are not
performed.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
SEE ALSO
csh(1), ksh(1), sh(1), attributes(5)
SunOS 5.10 15 Apr 1994 shift(1)