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https://github.com/alexst07/shell-plus-plus

A friendly and modern functional object oriented language for shell script.
https://github.com/alexst07/shell-plus-plus

command-line glob glob-pattern language programming-language scripting-language shell shell-script shellscript terminal

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A friendly and modern functional object oriented language for shell script.

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README 

        
# Introduction



Shell++ is a programming language that aims bring features from modern languages,

as facility to manipulate data structures, object oriented programming,

functional programming and others, to shell script.

https://alexst07.github.io/shell-plus-plus/



# Features

 * easy to manipulate data structure, as in Python

 * lambda functions

 * classes

 * executes commands like in Bash

 * pipe, redirection to or from files, sub shell

 * dynamic typing

 * glob and recursive glob

 * closures

 * reference counter

 * operator overriding



# Why another programming language?

I wanted a language that runs shell commands like Bash, and manipulate data structure with the ease of Python, I searched, but I did not find any that met my requirements, so I decided to use my free time to create one.



This is still in development, but it has already made life easier for me in many day-to-day tasks, maybe this might be useful for someone else, so I shared it on github.



However everything here can change without warning, because to date, the only purpose of it is MAKE MY LIFE EASIER AND ONLY THAT.



# Examples

Follows some examples just to get an idea of how the language works.



## A powerful glob

Shell++ has a powerful glob, that allows you to perform laborious tasks in a few lines. For example, suppose you want to modify the extension of all `txt` files to `csv` recursively.



```python

for p, [n] in G"**/*.txt" {

  mv ${p} ${p.parent_path()/"{n}.csv"}

}

```



## List comprehension

```shell

files = [f for f in $(ls) if path(f).size("M") > 50]

```

In this example files will be an array with all files listed by ls command with size bigger than 50Mb.



## Try-Catch

try catch helps you handle situations in an elegant way, for example, instead of giving a raw message to the user's face, you can treat the message that a command does not exist.



```php

try {

  git clone [email protected]:alexst07/shell-plus-plus.git

} catch InvalidCmdException as ex {

  print("git not installed [msg: {ex}]")

}

```

## Reading user input

```python

line = read()

print(line)

```



Function `read` is used to read user input, until the enter key is pressed, and the next line print the user input.



## Reading file line by line

```python

for line in file("example.txt") {

  print("line: {line}")

}

```



## Reading file line by line in shell style

```shell

shell {

  while let line = read() {

    print("line: {line}")

  }

} < example.txt

```



## Hello World

```shell

echo Hello World

print("Hello World")

```

In Shell++ you can use an other program as echo, or a native function print.



## String operations

### Length

```python

str = "example"

print("length: {len(str)}") # length: 7

```



### Upper case and lower case

```php

x = "HELLO"

echo ${x} # HELLO

echo ${x.lower()} # hello

echo ${x.upper()} # HELLO

```



### Substring

```python

str = "string test"

str1 = str[2:] # ring test"

str2 = str[:-2] # string te

str3 = str[2:4] # ri

```



### Replace

```python

filename = "Path of the bash is /bin/bash"

print("After Replacement: {filename.replace('bash', 'sh')}")

# After Replacement: Path of the sh is /bin/sh

print("length: {len(str)}")

```



### Pass variables to command

```php

echo ${t} # Hello

echo ${t + " World"} # Concatenate string

# ${} solve an expression and return the value to echo

```



## Command examples

### Pipeline

```shell

echo "Test" | cat # simple pipeline

ls src* | grep -e "test" # using glob



# using variables content as command

cip = "ipconfig"

cgrep = ["grep", "-e", "10\..*"]

${cip} | ${cgrep} # pass an array to command

```



### Redirecting to and from file

```shell

cat < filename.txt

cat < filename.txt | grep test

cat < filename.txt | grep test > result.txt



# using variables

filename = "filename.txt"

result = "result.txt"

cat < ${filename} | grep test > ${result}

```

### Concatenate file



```shell

echo line1 > test.txt

echo lene2 >> test.txt

```

test.txt has this content:

line1

lene2



### Redirecting error output

```shell

prog_test 2> /dev/null

```

Any output on stderr go to /dev/null.



### Assign command to variable

```php

p = $(prog_test -opt 1)



# check result

if p {

  print(p)

} else {

  print("error: {p.err()}")

}

```

Check the status result of the command prog_test, if prog_test

exited normally with status 0, the result is true and the line

print(p) is executed, if not, the else is executed.



### Iterating command result

```php

for f in $(ls -a mypath) {

  print("file: {f}")

}

```

Print all lines generated by ls command.



### Execute command from simple variabel

```shell

ex = "ls"

${ex} # execute ls commad

```



### Execute command from array variabel

```shell

scp = ["sch", "-i", "path/file.pem", "user@addr:path"]

${scp} # execute command from iterator

```

It is possible execute a command from an array, using this feature

you have much more flexibility to mount the command with its arguments

using arrays.



### Glob and recursive glob

```shell

file *.txt

```

Glob in this case works like in bash.



```shell

for f in g"**/*.txt" {

  file ${f}

}

```

iterate over all txt files recursively



```shell

file **/*.txt

```

This peace of code has the same output from above



## Path

### Check if a path or file exists

```php

if path("/home/me/file.txt").exists() {

  print ("file exists")

}

```



### Smart path comparison

```php

p1 = path("/home/../home/me/file.txt")

p2 = path("/home/me/file.txt")



print(p1 == p2) # true



p1 = p"/home/me/file.txt"

p2 = p"/home/me/file2.txt"



print(p1 == p2) # false

```

In Shell++ you can compare relatives path, it means,

using path object you compare path not string.



## Array

In Shell++ is easy create and access array, it works like in Python



```python

array1 = ['physics', 'chemistry', 1997, 2000];

array2 = [1, 2, 3, 4, 5, 6, 7 ];



print("array1[0]: {array1[0]}")

print("array2[1:5]: {array2[1:5]}")

```

Output:

```

array1[0]:  physics

array2[1:5]:  [2, 3, 4, 5]

```



## Map

Map is a hash map object, it works like dictionary in Python.



```python

m = {'Name': 'Zara', 'Age': 7, 'Class': 'First'}



print("m['Name']: {m['Name']}")

print("m['Age']: {m['Age']}")

```

Output:

```

m['Name']:  Zara

m['Age']:  7

```



## Functions

In Shell++ function is not a command as in Bash, functions in Shell++ are similar with Python.

```go

func test(a, b = 5) {

  m = {"sum": a+b, "sub":a-b}

  return m

}



print(test(6)["sum"])

```

Output:

```

11

```



### Lambda

Return a closure function

```go

func ftest(a) {

  v = ["echo", "ls", a]



  # closures

  return func(x) {

    return v.append(x)

  }

}

```



The keyword lambda is valid too. This example convert all array elements to

upper case string.

```python

vec = ["apple", "orange", "grape"]

vec.map(lambda x: x.to_upper())

```



## Classes

```php

# Complex number

class Complex {

  func __init__(r, i) {

    this.r = r

    this.i = i

  }



  func __add__(n) {

    return Complex(n.r + this.r, n.i + this.i)

  }



  func __sub__(n) {

    return Complex(n.r - this.r, n.i - this.i)

  }



  func __print__() {

    return "{string(this.r)} {string(this.i)}i"

  }

}



c1 = Complex(2, 3)

c2 = Complex(1, 2)

c = c1 + c2



print(c)

```

Output:

```

3 + 5i

```



## Quick-sort



```go

func quicksort(A, lo, hi) {

  if lo < hi {

    p = partition(A, lo, hi)

    A = quicksort(A, lo, p - 1)

    A = quicksort(A, p + 1, hi)

  }



  return A

}



func partition(A, lo, hi) {

  pivot = A[hi]

  i = lo

  j = lo



  for j in range(lo, hi) {

    if A[j] <= pivot {

      A[i], A[j] = A[j], A[i]

      i = i + 1

    }

  }



  A[i], A[hi] = A[hi], A[i]

  return i

}



a = [1,4,6,4,10,11,22,100,3,3,9]

print(quicksort(a, 0, len(a) - 1))

```

Output:

```

[1, 3, 3, 4, 4, 6, 9, 10, 11, 22, 100]

```



## Check if a command exists

If you need execute a no standard application, sometimes you need to check if the application is installed, with Shell it is a way.



```php

func exist_cmd(name) {

  c = $(which ${name})



  if string(c) == "" {

    return false

  }



  return true

}



print("Does cmd exist?")

print("ls: {exist_cmd('ls')}")

print("non-exist-cmd { exist_cmd('non-exist-cmd')}")

```

the command which inside $() have as result an cmd object, you can convert its result to string and handle it.

# Building



## Requirements:

  * A compiler that supports C++ 14 (gcc or clang)

  * Boost

  * Readline

  * CMake

  * Linux



## Compiling



### Ubuntu

First you need intall the requirements to build Shell++

```

# apt-get install -y build-essential

# apt-get install -y libboost-all-dev libreadline6 libreadline6-dev git cmake

```



With the requirements installed, make a clone of the repository

```

$ git clone [email protected]:alexst07/shell-plus-plus.git

```

After the clone, change to directory of the project

```

$ cd shell-plus-plus

```

To compile the project, you need create a directory when the cmake files will

be generated, and so, build the project



```

$ mkdir build

$ cd build

$ cmake ..

$ make

```

Now you can already use the Shell++, the binary is generated at shell/ directory.

To use Shell++ to execute a script, first, create an example script called my.shpp.



```

echo my first script in shell++

```

In the build path, call the binary to execute your script



```

$ ./shell/shpp my.shpp

```

You should see the output:

```

my first script in shell++

```

If you saw this output your build is working, if you want install Shell++.



```

$ sudo make install

```