Are you using the restart.sh from sa-mp wiki ? If yes, did you edit the sa-mp path to the one where your samp03svr binary is located ? A mis-leading path could have caused that error.
I guess I found the cause which triggered this error, open your shell file and locate this "#!/bin/sh"
remove "sh" and replace it with "bash", that's the name of the shell environment of your linux machine [unless if you've installed another shell], so it should look like #!/bin/bash" without the quotes ofcourse.