Is there a list of 'if' switches anywhere?

Question

Is there a list of all the if switches for use in Bash scripting? Sometimes I see someone using it and I wonder what the switch they're using actually does.

An example is the -z in this one. I know how to use it, but I don't know where it was derived from.

if [ -z "$BASH_VERSION" ]; then     echo -e "Error: this script requires the BASH shell!"     exit 1 fi 

Any references, guides, posts, answers would be appreciated.

Answer 1

Look at the Bash man page (man bash). The options are specified in the CONDITIONAL EXPRESSIONS section:

CONDITIONAL EXPRESSIONS        Conditional expressions are used by the [[  compound  command  and  the        test  and [ builtin commands to test file attributes and perform string        and arithmetic comparisons.  Expressions are formed from the  following        unary  or  binary  primaries.   If any file argument to one of the pri-        maries is of the form /dev/fd/n, then file descriptor n is checked.  If        the  file  argument  to  one  of  the  primaries  is one of /dev/stdin,        /dev/stdout, or /dev/stderr, file descriptor 0, 1, or 2,  respectively,        is checked.         Unless otherwise specified, primaries that operate on files follow sym-        bolic links and operate on the target of the link, rather than the link        itself.         -a file               True if file exists.        ... more options ... 

It is also explained in the help:

$ help [ [: [ arg... ]     This is a synonym for the "test" builtin, but the last     argument must be a literal `]', to match the opening `['. 

Answer 2

Yes. These are called conditional expressions and these are used by the [[ compound command and the test and [ builtin commands ([ is simply a synonym for test).

Read section 6.4 Bash Conditional Expressions of the Bash Reference Manual, which contains a list of all these switches and their usage.