bash-utils/shtpl/README.md

# shtpl
> bash templating

## Install

Clone or download this repository:

`git clone $p2git/dig/bash-utils.git`

Put the `shtpl` script somewhere meant for executable scripts like `/usr/local/bin/shtpl`.
Make it executable: `chmod +x shtpl`.

or let the installer do it for you :)
`bash-utils/shtpl/install`


## Usage

Create a template file to be executed with shtpl:

```
nano someTpl.shtpl
```
```
#!/usr/bin/env shtpl
Hello $WHO !
```

Make the template executable:
```
chmod +x someTpl.shtpl
```
... and execute it with some environment variables:
```
WHO=Doctor ./someTpl.shtpl
```
```
> Hello Doctor !
```

In case of many variable you can write 1 var on each line, but for bash to understand you have to escape the newlines and keep 1 space before:

```
VAR1=foo \
VAR2=bar \
VAR3=baz \
VAR4=aze \
./someTpl.shtpl
```

To save the result simply redirect to sdtout to a file:
```
WHO=Doctor ./someTpl.shtpl > doctorGreetings.txt
```


## Templating syntax

shtpl uses a hack to turn you file into a call of `echo "<your file here>"`, so it is simple, all what your system is able to understand as substitution is valid !

```
#!/usr/bin/env shtpl
Simple variable: $ENV_VAR , and with brackets: ${TOTO}cm²

Sub commands: $(echo ok)

Prompt user input in place: $(read -r -p Type\ some\ text\ : v;echo $v)

Loops: $(
for ((i=0 ; $MAX_LOOP - $i ; i++))
    do
	echo "[$i]"
done
)

Call sub templates: $(VAR_TO_PASS=$SOME_VAR ./myOtherTemplate.shtpl)
```
```
ENV_VAR=foo \
TOTO=42 \
MAX_LOOP=10 \
SOME_VAR=aze \
./someTpl.shtpl
```
Returns:
```
Simple variable: foo , and with brackets: 42cm²

Sub commands: ok

Prompt user input in place: your input

Loops: [0][1][2][3][4][5][6][7][8][9][10]

Call sub templates: what the template returns with "aze"
```

## Additional helper functions

SHTPL declares somme utility functions to use in templates as a sub-commands,
generally it is a 1 argument function that can be piped:

### lowerCase
To transform a string in lowercase:
```
Original value: $value
Lowercase value: $(lowerCase $value)
Lowercase piped: $(echo $value | lowerCase)
```

### slug
To transform a string in a safe name, special characters are turned into "_":
```
Original value: $value
Slug value: $(slug $value)
Slug piped: $(echo $value | slug)
```

### user-input
Asks the user to enter text input at template execution and put it in place,
multiline text is supported because you'd have to type (ctrl-D) to validate input:
```
You entered: $(user-input Enter a value)
and the 2nd time this: $(user-input 'Question with simple quote')
the last one is turned to lowercase: $(user-input To be turned in lowercase | lowerCase)
```