<p dir="ltr">It's for perfecting a shell script. Learning is not the right word. </p>
<p dir="ltr">Since it is for perfecting, many suggestions will be there related to shell globbing. Try to incorporate, it's better that way and might help at some point to avoid ambiguity (shell's intelligence, which is dependent on how a shell is created or compiled in the first place, is somewhat in question here).<br></p>
<p dir="ltr">It won't create any performance difference, however, specific shells might behave unexpectedly if this is not taken into consideration.</p>
<p dir="ltr">Try using the script without making any change to script in some random distribution for the same behaviour (maybe freebsd, archlinux, etcetera).<br>
You may or may not feel the need for incorporating those suggestions but that's how you can check more or less.<br>
Thats what I can think of right now.</p>
<div class="gmail_quote">On Apr 26, 2016 7:02 PM, "曹勇" <<a href="mailto:ycao18@stevens.edu">ycao18@stevens.edu</a>> wrote:<br type="attribution"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">I just find <a href="http://www.shellcheck.net" target="_blank">http://www.shellcheck.net</a> is an awesome website for learning shell.<div>But it recommend use double quote for most case when I use ‘$'</div><div><br></div><div><span style="color:rgb(192,192,192);font-family:Consolas,'Courier New',monospace;font-size:13px;background-color:rgb(0,0,0)">$ shellcheck myscript</span><br style="color:rgb(192,192,192);font-family:Consolas,'Courier New',monospace;font-size:13px"><span style="color:rgb(192,192,192);font-family:Consolas,'Courier New',monospace;font-size:13px;background-color:rgb(0,0,0)"> </span><br style="color:rgb(192,192,192);font-family:Consolas,'Courier New',monospace;font-size:13px"><a style="text-decoration:underline;color:rgb(128,128,255);font-family:Consolas,'Courier New',monospace;font-size:13px">Line 1:</a><br style="color:rgb(192,192,192);font-family:Consolas,'Courier New',monospace;font-size:13px"><span style="color:rgb(192,192,192);font-family:Consolas,'Courier New',monospace;font-size:13px;background-color:rgb(0,0,0)">ssh $EC2_BACKUP_FLAGS_SSH -o StrictHostKeyChecking=no -v ubuntu@$EC2_HOST \</span><br style="color:rgb(192,192,192);font-family:Consolas,'Courier New',monospace;font-size:13px"><span style="color:rgb(32,255,32);font-family:Consolas,'Courier New',monospace;font-size:13px"> ^-- <a href="https://github.com/koalaman/shellcheck/wiki/SC2086" style="color:rgb(128,128,255)" target="_blank">SC2086</a>: Double quote to prevent globbing and word splitting.</span><br style="color:rgb(192,192,192);font-family:Consolas,'Courier New',monospace;font-size:13px"><span style="color:rgb(32,255,32);font-family:Consolas,'Courier New',monospace;font-size:13px"> ^-- <a href="https://github.com/koalaman/shellcheck/wiki/SC2086" style="color:rgb(128,128,255)" target="_blank">SC2086</a>: Double quote to prevent globbing and word splitting.</span></div><div><span style="color:rgb(32,255,32);font-family:Consolas,'Courier New',monospace;font-size:13px"><br></span></div><div><font face="Consolas, Courier New, monospace" size="2">We really need use double quote in this case?</font></div></div><br>_______________________________________________<br>
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