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December
22, 2003 -
Managing Variable Attributes with typeset
- Part II
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In
addition to controlling the case
(lower/upper) of a variable, it is often
useful to specify the justification and
also the width if desired. These
attributes are set by using the -L and -R
options. The width may optionally be
defined by adding a numeric value
immediately after the -L or -R.
In this first example, the variable
MY_VAR1 is defined to be left justified
and has a maximum length of 5 characters:
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$ typeset -R5 MY_VAR1
$ BORDER="|"
$ MY_VAR1="owl"
$ print "${BORDER}${MY_VAR1}${BORDER}"
| owl|
$
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A
variable named BORDER was used to show you
that the shell will pad unused character
positions with spaces. In the next
example, notice how the shell truncates
the variable to maintain the pre-defined
width of 5:
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$ typeset -L5 MY_VAR2
$ BORDER="|"
$ MY_VAR2="falcon"
$ print "${BORDER}${MY_VAR2}${BORDER}"
|falco|
$
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If
a width is not specified for a variable, the
shell defines it to be the length of the
first value assigned to it:
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$ typeset -L MY_VAR3
$ BORDER="|"
$ MY_VAR3="raptor"
$ print "${BORDER}${MY_VAR3}${BORDER}"
|raptor|
$ MY_VAR3="eagle"
$ print "${BORDER}${MY_VAR3}${BORDER}"
|eagle |
$
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