10 		

    11 		

    12 		<h3>relpipe-in-cli: Hello Wordl!</h3>

    13 		

    14 		<p>

    15 			Let's start with and obligatory Hello World example.

    16 		</p>

    17 		

    18 		<m:pre jazyk="bash"><![CDATA[relpipe-in-cli generate "relation_from_cli" 3 \

    19 	"a" "integer" \

    20 	"b" "string" \

    21 	"c" "boolean" \

    22 	"1" "Hello" "true" \

    23 	"2" "World!" "false"]]></m:pre>

    24 	

    25 		<p>

    26 			This command generates relational data.

    27 			In order to see them, we need to convert them to some other format.

    28 			For now, we will use the "tabular" format and pipe relational data to the <code>relpipe-out-tabular</code>.

    29 		</p>

    30 		

    31 		<m:pre jazyk="bash"><![CDATA[relpipe-in-cli generate "relation_from_cli" 3 \

    32 		"a" "integer" \

    33 		"b" "string" \

    34 		"c" "boolean" \

    35 		"1" "Hello" "true" \

    36 		"2" "World!" "false" \

    37 	| relpipe-out-tabular]]></m:pre>

    38 	

    39 		<p>Output:</p>

    40 

    41 		<pre><![CDATA[relation_from_cli:

    42  ╭─────────────┬────────────┬─────────────╮

    43  │ a (integer) │ b (string) │ c (boolean) │

    44  ├─────────────┼────────────┼─────────────┤

    45  │           1 │ Hello      │        true │

    46  │           2 │ World!     │       false │

    47  ╰─────────────┴────────────┴─────────────╯

    48 Record count: 2

    49 ]]></pre>

    50 

    51 		<p>

    52 			The syntax is simple as we see above. We specify the name of the relation, number of attributes,

    53 			and then their definitions (names and types),

    54 			followed by the data.

    55 		</p>

    56 		

    57 		<h3>relpipe-in-cli: STDIN</h3>

    58 		

    59 		<p>

    60 			The number of CLI arguments is limited and their are passed at once to the process.

    61 			So there is option to pass the values from STDIN instead of CLI arguments.

    62 			Values on STDIN are expected to be separated by the null-byte.

    63 			We can generate such data e.g. using <code>echo</code> and <code>tr</code> (or using <code>printf</code> or other commands):

    64 		</p>

    65 		

    66 		<m:pre jazyk="bash"><![CDATA[echo -e "1\nHello\ntrue\n2\nWorld\nfalse" \

    67 	| tr \\n \\0 \

    68 	| relpipe-in-cli generate-from-stdin relation_from_stdin 3 \

    69 		a integer \

    70 		b string \

    71 		c boolean \

    72 	| relpipe-out-tabular]]></m:pre>

    73 

    74 		<p>

    75 			The output is same as above.

    76 			We can use this approach to convert various formats to relational data.

    77 			There are lot of data already in the form of null-separated values e.g. the process arguments:

    78 		</p>

    79 		

    80 		<m:pre jazyk="bash"><![CDATA[cat /proc/$(pidof mc)/cmdline \

    81 	| relpipe-in-cli generate-from-stdin mc_args 1 a string \

    82 	| relpipe-out-tabular

    83 ]]></m:pre>

    84 	

    85 		<p>If we have <code>mc /etc/ /tmp/</code> running in some other terminal, the output will be:</p>

    86 		

    87 		<pre><![CDATA[mc_args:

    88  ╭────────────╮

    89  │ a (string) │

    90  ├────────────┤

    91  │ mc         │

    92  │ /etc/      │

    93  │ /tmp/      │

    94  ╰────────────╯

    95 Record count: 3]]></pre>

    96 

    97 		<p>

    98 			Also the <code>find</code> command can produce data separated by the null-byte:

    99 		</p>

   100 		

   101 		<m:pre jazyk="bash"><![CDATA[find /etc/ -name '*ssh*_*' -print0 \

   102 	| relpipe-in-cli generate-from-stdin files 1 file_name string \

   103 	| relpipe-out-tabular]]></m:pre>

   104 	

   105 		<p>Will display something like this:</p>

   106 		

   107 		<pre><![CDATA[files:

   108  ╭───────────────────────────────────╮

   109  │ file_name                (string) │

   110  ├───────────────────────────────────┤

   111  │ /etc/ssh/ssh_host_ecdsa_key       │

   112  │ /etc/ssh/sshd_config              │

   113  │ /etc/ssh/ssh_host_ed25519_key.pub │

   114  │ /etc/ssh/ssh_host_ecdsa_key.pub   │

   115  │ /etc/ssh/ssh_host_rsa_key         │

   116  │ /etc/ssh/ssh_config               │

   117  │ /etc/ssh/ssh_host_ed25519_key     │

   118  │ /etc/ssh/ssh_import_id            │

   119  │ /etc/ssh/ssh_host_rsa_key.pub     │

   120  ╰───────────────────────────────────╯

   121 Record count: 9]]></pre>