Shell_grep

search in globe and print

• Script

    #!/bin/bash
    # cgrep-- 顯示前後文並且符合模板的全域搜索和列印指令
  
     context=0
  
     esc="^["
  
     boldon="${esc}[1m"
  
     boldoff="${esc}[22m"
  
     tempout='/tmp/cgrep.$$'
  
     sedscript='/tmp/cgrep.sed.$$'
  
     function MatchOrNot
     {
  
       matches=0
  
       echo "s/$pattern/${boldon}$pattern${boldoff}/g" >$sedscript
  
       for lineon in $(grep -n "$pattern" $1 | cut -d: -f1) #(a) 
       do
           if [ $context -gt 0 ]; then
              prev="$(( $lineon - $context))"
  
  
                 if [ $prev -lt 1]; then
                    prev="1"
  
                 fi
                   next="(( $lineon + $context ))"
  
                 if [ $matches -gt 0]; then
                 echo "${prev}i\\" >> $sedscript #(b) 
  
                 fi
                  echo "${prev,${next}p}" >> $sedscript
  
  
           else
             echo "${lineon}p" >> $sedscript #(c) 
  
  
           fi
            matches="$(( matches +1 ))"
       done
  
       if [$matches -gt 0]; then
          sed -n -f $sedscript $1 | uniq | more #(d)
       fi
  
      }
  
  
      exit 0
  

• Syntax

  • (a) grep -n

    取得所有符合模板文字的行號。

  • (b)

    ${}i
    
    ${}p
    
    // to be continued...
    

  • (c)

    https://github.com/QueenieCplusplus/Shell_echo/blob/master/README.md#--

      command > file redirects a command’s output to a file (overwriting any existing content).
    
      command >> file appends a command’s output to a file.
    

  • (d)

       first | second is a pipeline: the output of the first command is used as the input to the second.
    

• Execution Scripts

    -c <line_number>
  

指定要顯示前後文的行數。

此腳本可接受輸入串流或是檔案，可將串流暫存至暫存檔案，方才處理暫存檔案，抑或是命令列指定檔案（可指定一個或是多個檔案）。

    $ cgrep -c 1 tea tea.txt

Ref Doc

https://swcarpentry.github.io/shell-novice/reference/