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PObash script: How to implement your own history mechanism?
 

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    <p>I'm implementing an interactive bash script similar to the MySQL client, <code>/usr/bin/mysql</code>. In this script I need to issue various types of 'commands'. I also need to provide a history mechanism whereby the user can use the up/down arrow keys to scroll through the commands entered so far.</p> <p>The snippet listed here (<a href="http://tldp.org/LDP/abs/html/internal.html" rel="nofollow">Example 15-6, Detecting the arrow keys</a>) does not exactly do what I want it to. I really want the following:</p> <ol> <li><p>The up/down arrow keys should operate in silent mode. Meaning, they should not echo their character codes on the terminal. </p></li> <li><p>The other keys however (which will be used to read the command names and their arguments) <strong>must not</strong> operate in silent mode.</p></li> </ol> <p>The problem with <code>read -s -n3</code> is that it does not satisfy my simultaneously conflicting requirements of silent mode <strong>and</strong> echo mode, based solely on the character code. Also, the value <code>-n3</code> will work for arrow keys but, for other/regular keys, it won't 'return control' to the calling program until 3 characters have been consumed.</p> <p>Now, I could try <code>-n1</code> and manually assemble the input, one character at a time (yuck!). But the character-code based silent-/echo-mode switching problem would still persist!</p> <p>Has anyone attempted this thing in bash? (Note: I cannot use C, nor other scripting languages like Perl, Python, etc.)</p> <p><strong>EDIT</strong></p> <p>Continuing with Dennis' answer... You will <em>also</em> need to <em>manually</em> add your desired entries to your history via <code>history -s</code>, like so...</p> <pre><code>while read -e x; do history -s "$x" # ... done </code></pre>
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