shell - how to use the if statement for error and warning messages in bash -

i writing codes on gedit , want latest error , warning messages using if statement, if theres error should warning messages.

cp /volumes/documents/criticalfile.txt /volumes/backup/.  if [ "?" != 0 ];      echo "[error] copy failed!" 1>&2      exit 1  fi

i've used above code not sure if correct or not.

you have use

if [ "$?" != 0 ];

instead of

 if [ "?" != 0 ];

let want copy file don't know if error. use below command

cp -f /root/desktop/my_new_file */root/t

definitely give me error because copying "*/root/t" not possible.

i can check using following codes

#!/bin/bash cp -f /root/desktop/my_new_file */root/t if [ "$?" = 0 ];then echo "no error" else echo "we have  error!" fi

my output (note condition working)

cp: cannot create regular file `*/root/t': no such file or directory have  error

now let want copy file possible location like

cp -f /root/desktop/my_new_file /root/t

i no error cp command

output

no error

Crty