Hi,
I have this script :

Nbr_BD_Link=`
sqlplus -S sysadm/${PSWD}@${DB_Name} << EOF
        set head off feedback off  ;
        select count(*) from dba_db_links ;
        exit ;
EOF `
echo "Nbr_BD_Link is : "
echo ${Nbr_BD_Link}
echo "we do a test"
if [ "${Nbr_BD_Link}" != "0" ] ; then
echo "${T80}\nLa base ${DB_Name} contient ${Nbr_BD_Link} DB Link :"
fi

Nbr_BD_Link is :
0
we do a test
--------------------------------------------------------------------------------
La base MYDB contient
         0 DB Link :

Nbr_BD_Link=0
Nbr_BD_Link=`
sqlplus -S sysadm/${PSWD}@${DB_Name} << EOF
        set head off feedback off  ;
        select count(*) from dba_db_links ;
        exit ;
EOF `
echo "Nbr_BD_Link is : "
echo ${Nbr_BD_Link}
echo "we do a test"
Nbr_BD_Link=0
if [ "${Nbr_BD_Link}" != "0" ] ; then
echo "${T80}\nLa base ${DB_Name} contient ${Nbr_BD_Link} DB Link :"
fi

Nbr_BD_Link is :
0
we do a test

As you can see from the output and expect from your script, it has a leading newline and some spaces. Take out the newline just after the opening backtick and/or use a comparison operator which is slightly less picky about whitespace (I tend to recommend case over if test).

Thank you.
How Take out the newline just after the opening backtick ?
iTRIED FOR CASE /
:man case
Manual entry for case not found or not installed.
[:man select
Manual entry for select not found or not installed.
[:man CASE
Manual entry for CASE not found or not installed.

case is a shell built-in, like if and while; it's documented in the sh manual page. If you have bash (or, I suppose, any of a number of other modern shells), try help case

You have a newline before "sqlplus"; by "take out the newline" I meant, move the sqlplus command to the same line as the opening backtick.

Nbr_BD_Link=`sqlplus -S sysadm/${PSWD}@${DB_Name} << EOF
        set head off feedback off  ;
        select count(*) from dba_db_links ;
        exit ;
EOF `
echo "Nbr_BD_Link is '${Nbr_BD_Link}'"
echo "we do a test"
case ${Nbr_BD_Link} in
  *[1-9]*) echo "${T80}\nLa base ${DB_Name} contient ${Nbr_BD_Link} DB Link :" ;;
esac

Thank you.