title: grep with or and fixed
body: <p>Actually i have tried to grep different files name but its not working with grep just because of brackets while its worked for <strong>match</strong> </p>
  
  <pre><code> match("248465_abc_S(R).doc",Role[,"Name.of.file"])
     [1] 9
     grep("248465_abc_S(R).doc",Role[,"Name.of.file"])
     integer(0)
  </code></pre>
  
  <p>as i have different format as in doc,docx so i cant use match, i used <strong>fixed=T</strong> ,its working with single name but not with <strong>OR</strong></p>
  
  <pre><code>grep("248465_abc_S(R)",Role[,"Name.of.file"],fixed = TRUE)
  [1] 9
  grep(paste(names,collapse="|"),Role[,"Name.of.files"]) #some names still missing because of brackets
  [1]  6 11 14 17 26 27 28
  grep(paste(names,collapse="|"),Role[,"Name.of.files"],fixed = TRUE)
  integer(0)
  </code></pre>
  
  <p><strong>EDIT</strong></p>
  
  <pre><code>paste(name,collapse="|")
  [1] "115457_dfm(R)|248465_sdj_S(R)[1]|248471_sdjb(R)[1]|28837_FS
  grep(paste(gsub("]","\\]",gsub("[","\\[",gsub(".","\\.",gsub(")","\\)",gsub("(","\\(",name,fixed=T),fixed=T),fixed=T),fixed=T),fixed=T),collapse="|"),Role[,"Name.of.files"])
  [1]  6  9 10 11 12 14 17 18 20 21 22 26 27 28
  </code></pre>
  
  <p>instead of indentify <strong>each and every character</strong> to escaped ,Is their any better approach,thanks.</p>