title: Prepend file names with plus sign
body: <p>I want to add a <code>+</code> (plus sign) before all the occurrences of image names in a huge file, using <code>sed</code>.</p>
  
  <p>This is an example of one line:  </p>
  
  <pre><code>DAUSSI-H22-14K White Gold-Princess-1.00ct-G-SI1orH-VS2-EGL-mm-3.5,,H22,,7050,5720,3/5/2012 7:34,,,1,,henri-daussi-h22-diamond-halo-engagement-ring-14k-white-gold-width--mm-style-princess-1-00ct-g-si1-or-h-vs2-egl-size-3-5,henri-daussi-h22-diamond-halo-engagement-ring-14k-white-gold-width--mm-style-princess-1-00ct-g-si1-or-h-vs2-egl-size-3-5.html,Henri Daussi H22 Diamond Halo Engagement Ring-14K White Gold-Style:Princess-1.00ct-G-SI1 or H-VS2-EGL-Width: mm-Size:3.5,"Henri Daussi engagement ring with hand-matched side diamonds in a beautiful halo setting, totaling 1.40 carats. The image at left displays this ring with a 1.00 carat princess cut diamond. This setting can accommodate a variety of shapes and sizes. Please contact us on the range of possibilities of any ring.","Henri Daussi engagement ring with hand-matched side diamonds in a beautiful halo setting, totaling 1.40 carats. The image at left displays this ring with a 1.00 carat princess cut diamond. This setting can accommodate a variety of shapes and sizes. Please contact us on the range of possibilities of any ring.",,,,,14K White Gold,Princess-1.00ct-G-SI1 or H-VS2-EGL,,3.5,Metal_Style_Width_Size,simple,/H22.jpg,Shown with a 1.00 carat princess cut diamond.,/H_22.jpg,Shown with a 1.00 carat princess cut diamond.,/H22.jpg,Shown with a 1.00 carat princess cut diamond.,,,,,,Enabled,Taxable Goods,Not Visible Individually,0,0,No,Engagement Rings/Henri Daussi;;Designers/Henri Daussi,No,"ROUND, PEAR SHAPE, EMERALD CUT, MARQUISE, OVAL, RADIANT, PRINCESS CUT, HEART SHAPE, CUSHION CUT, ASSCHER CUT",.45-6.00 Carat,/H22.jpg
  </code></pre>
  
  <p>For this line, the image is <code>/H22.jpg</code> and I want this string change to <code>+/H22.jpg</code>.</p>
  
  <p>As far as I can tell, all images start with <code>/</code>, but it's a huge file, I can't be totally sure. One thing I am sure of is that there is a comma before (it's a comma separated <code>.csv</code> file). So I need to substitute <code>,[any character except dot][dot](.jpg|.gif|.png)</code> with <code>,+[image_name].extension</code>.</p>
  
  <p>This is the best I've done so far:  </p>
  
  <pre><code>sed -ie 's/,\([a-zA-Z0-9/_]\+\)\(\.jpg|\.png|\.gif\)/,+\1\2/g' file.csv
  </code></pre>
  
  <p>but it's not working.</p>