Hiding output of a command

grill_gus

I have a script where it checks whether a package is installed or not and whether the port 8080 is being used by a particular process or not. I am not experienced at all with bash, so I did something like this: if dpkg -s net-tools; then if netstat -tlpn | grep 8080 | grep java; then echo "Shut down server before executing this script" exit fi else echo "If the server is running please shut it down before continuing with the execution of this...

Originally asked by dabadaba on Stack Exchange (askubuntu) (CC BY-SA 3.0).

uphilltech

Great question — answering as the UphillTech team:

To hide the output of any command usually the stdout and stderr are redirected to /dev/null . command > /dev/null 2>&1 Explanation: 1. command > /dev/null : redirects the output of command (stdout) to /dev/null 2. 2>&1 : redirects stderr to stdout , so errors (if any) also goes to /dev/null Note &>/dev/null : redirects both stdout and stderr to /dev/null . one can use it as an alternate of /dev/null 2>&1 Silent grep : grep -q "string" match the string silently or quietly without anything to standard output. It also can be used to hide the output. In your case, you can use it like, if dpkg -s net-tools > /dev/null 2>&1; then if netstat -tlpn | grep 8080 | grep java > /dev/null 2>&1; then...

Full answer by sourav c.: https://askubuntu.stackexchange.com/a/474566 (CC BY-SA 3.0).

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