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Diffstat (limited to 'doc/importas.html')
| -rw-r--r-- | doc/importas.html | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/doc/importas.html b/doc/importas.html index fa1cef7..850444d 100644 --- a/doc/importas.html +++ b/doc/importas.html @@ -32,7 +32,8 @@ environment variable, then executes another program. <ul> <li> <tt>importas</tt> fetches the value of <em>envvar</em> in the environment. If neither the <em>-D</em> nor the <em>-i</em> option is given, -and <em>envvar</em> is undefined, the <strong>null word</strong> is returned. </li> +and <em>envvar</em> is undefined, <strong>no word</strong> is returned +(that is different from the empty word). </li> <li> <tt>importas</tt> then performs <a href="el_substitute.html">variable substitution</a> on <em>prog...</em>, with <em>variable</em> as key and that string as value. @@ -42,11 +43,10 @@ with <em>variable</em> as key and that string as value. <h2> Options </h2> <ul> - <li> <tt>-D</tt> <em>default</em> : If <em>envvar</em> is -undefined, and this option is not given, substitute zero word for -<em>variable</em> instead of the empty word; and if it is given, -substitute <em>default</em> instead. To substitute the empty word, -use <tt>-D ""</tt>. </li> + <li> <tt>-D</tt> <em>default</em> : If this option is given and +<em>envvar</em> is undefined, substitute <em>default</em> for the value of +<em>variable</em> instead of no word. For instance, to substitute +the empty word, use <tt>-D ""</tt>. </li> <li> <tt>-i</tt> : Insist. If <em>envvar</em> is undefined, <tt>importas</tt> will not do anything; instead, it will exit 100 with an error message. This has precedence over any <tt>-D</tt> option. </li> @@ -58,5 +58,17 @@ the environment after the substitution. <tt>importas -u <em>variable</em> the substitution mechanism</a>. </li> </ul> +<h2> Notes </h2> + +<ul> + <li> When <em>envvar</em> is undefined, and the <tt>-D</tt> option is +not given, any <a href="el_substitute.html">variable substitution</a> +with <em>variable</em> as the key will return no word; that is true +even when the <tt>${<em>variable</em>}</tt> form to be substituted +happens in the middle of a word (with a prefix and/or a postfix), which +means the whole world will be deleted. If this is not the behaviour +you want, use the <tt>-D</tt> option. </li> +</ul> + </body> </html> |