bash stdin

multiple_stdin.md

• multiple stdin to single output

  $ cat test.dat
  Test
  Multiple
  input
  
  $ cat test.dat | ./multiple_stdin_to_single_output.sh
  Test Multiple input
  
  $ cat multiple_stdin_to_single_output.sh
  #!/bin/sh
  
  myvar=`cat`
  echo $myvar
  

• multiple stdin to multiple output

  $ cat test.dat | ./multiple_stdin_to_multiple_output.sh
  Test
  Multiple
  input
  
  $ cat multiple_stdin_to_multiple_output.sh
  #!/bin/sh
  
  while read query
  do
    echo $query
  done
  

split_by_tab.md

• multiple stdin to output splitted by tab

  $ cat test.query
  갤빈클라인      캘빈클라인
  제첩국  재첩국
  
  $ cat test.query | ./test.sh
  갤빈클라인      캘빈클라인
  갤빈클라인
  캘빈클라인
  제첩국  재첩국
  제첩국
  재첩국
  
  $ cat test.sh
  #!/bin/sh
  
  while read query
  do
    echo "$query"
    norm="${query%$'\t'*}"
    oup="${query##*$'\t'}"
    echo $norm
    echo $oup
  done
  

• how to split a string in shell and get the last field

string_manipulation.sh

#!/bin/sh

url='https://www.abc.com/123'
echo $url
protocol_removed=${url##*:}
echo $protocol_removed
slash_removed=${protocol_removed:2:${#protocol_removed}}
echo $slash_removed
slash_changed=${slash_removed/\//-}
echo $slash_changed

# Result
# https://www.abc.com/123
# //www.abc.com/123
# www.abc.com/123
# www.abc.com-123