Shell Test Flags

Flags you can use with the test command, e.g.

if test -e /path/to/file; then
    echo "file exists"
fi

File Tests

`-d file`	True if `file` exists and is a directory
`-e file`	True if `file` exists
`-f file`	True if `file` exists and is a regular file
`-L file`	True if `file` exists and is a symlink
`-s file`	True if `file` exists and has size greater than zero
`-x file`	True if `file` exists and is executable

String Tests

`-n string`	True if `string` has non-zero length
`-z string`	True if `string` has zero length
`string1 = string2`	True if the strings are identical
`string1 != string2`	True if the strings are not identical

Numerical Tests

`int1 -eq int2`	True if the integers are equal
`int1 -ge int2`	True if `int1` is greater than or equal to `int2`
`int1 -gt int2`	True if `int1` is greater than `int2`
`int1 -le int2`	True if `int1` is less than or equal to `int2`
`int1 -lt int2`	True if `int1` is less than `int2`
`int1 -ne int2`	True if the integers are not equal

Operators

The negation operator is !, e.g.

if test ! -e /path/to/file; then
    echo "file does not exist"
fi

The test command may support -a and -o operators for boolean AND and OR, but these are not portable. For boolean logic, use multiple invocations of the test command with the shell operators && and ||, e.g.

if test -e file1 && test -e file2; then
    echo "both files exist"
fi

if test -e file1 || test -e file2; then
    echo "at least one file exists"
fi

Aliases

The bracket command, [, is an alias for test, e.g.

if [ -e /path/to/file ]; then
    echo "file exists"
fi

The trailing bracket ] must be included and both brackets must be offset by spaces.

Although often seen in the wild, this bracket alias manages to be both useless and error-prone. There's never a reason to use it.