title: bash substitute first character in every line
body: <p>My file looks like this:</p>
  
  <pre><code>  1 chrX_73833098_73834098
    1 chrX_73889652_73890652
    1 chrX_91194501_91195501
    1 chrX_92000157_92001157
    1 chrX_92106500_92107500
  </code></pre>
  
  <p>I want to replace first character "1" into 0. Wanted output is :</p>
  
  <pre><code>  0 chrX_73833098_73834098
    0 chrX_73889652_73890652
    0 chrX_91194501_91195501
    0 chrX_92000157_92001157
    0 chrX_92106500_92107500
  </code></pre>
  
  <p>Trying to do it with this:</p>
  
  <pre><code>sed 's/^./0/g' file
  </code></pre>
  
  <p>But the output is:</p>
  
  <pre><code>0     1 chrX_73833098_73834098
  0     1 chrX_73889652_73890652
  0     1 chrX_91194501_91195501
  0     1 chrX_92000157_92001157
  0     1 chrX_92106500_92107500
  </code></pre>
  
  <p>I believe there is easy way to fix it, but I don't know it. </p>