Question

I am trying to execute a command using function calls in a shell script. When I pass the command to that function as an argument of that function, it does not work.

Function definition:

function ExecuteCommand() (

    # $1: User@Host
    # $2: Password
    # $3: Command to execute

    # Collect current IFS value
    OLD_IFS=$IFS

    # Set IFS value to new line feed
    IFS=$'\n'

    #Execute the command and capture the output
    EXPECT_OUTPUT=($(expect ssh_exec.expect $1 $2 $3))

    #Print the output
    OUTPUT_LINE_COUNT=${#EXPECT_OUTPUT[@]}
    for ((OUTPUT_LINE_INDEX=0; OUTPUT_LINE_INDEX<OUTPUT_LINE_COUNT; OUTPUT_LINE_INDEX++)) ;
    do
            echo ${EXPECT_OUTPUT[$OUTPUT_LINE_INDEX]}
    done

    # Get back to the original IFS 
    IFS=$OLD_IFS 

)

Function call:

ExecuteCommand oracle@192.168.***.*** password123 "srvctl status database -d mydb"  

And the output I get is:

spawn ssh oracle@192.168.***.*** {srvctl status database -d mydb}
oracle@192.168.***.***'s password: 
bash: {srvctl: command not found  

But when I don’t pass the command as an argument of the function, it works perfectly:

Function definition in that case:

function ExecuteCommand() (

    # $1: User@Host
    # $2: Password

    # Collect current IFS value
    OLD_IFS=$IFS

    # Set IFS value to new line feed
    IFS=$'\n'

    #Execute the command and capture the output
    EXPECT_OUTPUT=($(expect ssh_exec.expect $1 $2 srvctl status database -d mydb))

    #Print the output
    OUTPUT_LINE_COUNT=${#EXPECT_OUTPUT[@]}
    for ((OUTPUT_LINE_INDEX=0; OUTPUT_LINE_INDEX<OUTPUT_LINE_COUNT; OUTPUT_LINE_INDEX++)) ;
    do
            echo ${EXPECT_OUTPUT[$OUTPUT_LINE_INDEX]}
    done

    # Get back to the original IFS 
    IFS=$OLD_IFS 

)

Function call:

ExecuteCommand oracle@192.168.***.*** password123  

And I get the output just as I expected:

spawn ssh oracle@192.168.***.*** srvctl status database -d mydb
oracle@192.168.***.***'s password: 
Instance mydb1 is running on node mydb1
Instance mydb2 is running on node mydb2
Instance mydb3 is running on node mydb3

Please help me about what was wrong while passing the command as a function parameter here in the first case.

Answer 1

If I am not wrong, any argument to “expect” within double quotes gets replaced with curly braces. Hence, the expect command became like:

expect ssh_exec.expect oracle@192.168.***.*** {srvctl status database -d mydb}

which made the shell to interpret “{srvctl” as a command.

Try using it like this:

EXPECT_OUTPUT=($(expect ssh_exec.expect $*))

instead of

EXPECT_OUTPUT=($(expect ssh_exec.expect $1 $2 $3))

And call your function like:

ExecuteCommand oracle@192.168.***.*** password123 srvctl status database -d mydb