Shell judges whether the command is executed successfully

Determine whether the last command was successful

#!/usr/bin/env bash

#  This script is used to demonstrate :  Determine whether the last command was successful 

#  Whether the last command is not equal to 0
if [ $? -ne 0 ]; then
    echo "failed"
else
    echo "succeed"
fi

#  Whether the status of the previous command is equal to 0
if [ $? -eq 0 ]; then
    echo "succeed"
else
    echo "failed"
fi

#  Suggested code style :  If the command is not executed , Print execution failed 
if ! make mytarget; then
    echo "Build failed"
fi

shell Comparison operator

Reference resources : https://blog.mimvp.com/article/7415.html

Operator	explain
-eq	be equal to
-ne	It's not equal to
-gt	Greater than
-lt	Less than
ge	Greater than or equal to
le	Less than or equal to