linux - Reading and comparing column in .txt file in bash -

i got .txt file content is

5742060626,ms.pimpan tantivaravong,female

5742065826,ms.kaotip tanti,female

- create interface script add list in file first, have compare input id exitsting id in list. use cut command read 1st column of .txt file. but,i got problem when trying compare it.

here code.

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!/bin/bash # datafile='student-2603385.txt'  while read p;  if [ "$id" == (echo $p | cut -d, -f1) ]  echo 'duplicate id'  fi done <$datafile 

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could suggest me, how should do? thank you

your script has numerous quoting bugs, quote variable expansion when variable contains file name, expected when want avoid word splitting , pathname expansion shell.

letting aside, in if [ "$id" == (echo $p | cut -d, -f1) ]:

• you need command substitution, $() around echo ... | cut ..., not subshell ()

• you need quotes around $() prevent word splitting (and pathname expansion)

• == bash-ism, not defined posix, reminder

• try use [[ as possible, being shell keyword [[ handles word splitting

so test ([):

if [ "$id" == "$(echo "$p" | cut -d, -f1)" ] 

better:

if [[ $id == $(echo "$p" | cut -d, -f1) ]]