Test

"Test" is a conditional check in Bash

[ -e FILE ] - True if FILE exists [ -d FILE ] - True if FILE exists and is a directory. [ -f FILE ] - True if FILE exists and is a regular file (ie. not a directory). [ -z STRING ] - True if the length if "STRING" is zero. [ -n STRING ] or [ STRING ] - True if the length of string > 0

• use to check for existence of variable

http_status=$(curl ___)
if [ $http_status != "200" ]
    then
        echo "command failed"
fi

Test based on exit status of previously executed command

• The ? variable holds the exit status of the previously executed command (the most recently completed foreground process).

if [ $? -eq 0 ]
then echo 'That was a good job!'
fi

Using && and || for conditionals

Never use x && y || z when y can return a non-zero exit status. Use if statements instead

• source

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Children

1. Cook