Eis aqui um exemplo de sintaxes para 'if', 'for', 'while' nas linguagens, shell-script, perl, python e php:

+---+-------------------------+------------------------------------+--------------------------+-----------------------------------+
| * |        SHELL            |               PERL                 |          PYTHON          |                 PHP               |
+---+-------------------------+------------------------------------+--------------------------+-----------------------------------+
|   | #!/bin/bash             | #!/usr/bin/perl                    | #!/usr/bin/env python    | <?                                |
| I |                         |                                    |                          |                                   |
|   | if [ 1 = 1 ]; then      | if ( 1 eq 1 ){                     | if 1 == 1: print 'teste' | if( 1 == 1 ){                     |
| F |                         |                                    |                          |                                   |
|   |       echo "teste"      |    print "teste\n";                |                          |    echo "teste\n";                |
|   |                         |                                    |                          |                                   |
|   | fi                      | }                                  |                          | }                                 |
|   |                         |                                    |                          |                                   |
|   |                         |                                    |                          | ?>                                |
+---+-------------------------+------------------------------------+--------------------------+-----------------------------------+
|   | #!/bin/bash             | #!/usr/bin/perl                    | #!/usr/bin/env python    | <?                                |
| F |                         |                                    |                          |                                   |
|   | for i in `seq 10`; do   | for ( $i = 1 ; $i <= 10 ; $i++ ) { | for i in range(1,11):    | for ( $i = 1 ; $i <= 10 ; $i++ ){ |
| O |                         |                                    |                          |                                   |
|   |     echo $i             |        print "$i\n";               |       print i            |         echo "$i\n";              |
| R |                         |                                    |                          |                                   |
|   | done                    | }                                  |                          | }                                 |
|   |                         |                                    |                          |                                   |
|   |                         |                                    |                          | ?>                                |
+---+-------------------------+------------------------------------+--------------------------+-----------------------------------+
|   | #!/bin/bash             | #!/usr/bin/perl                    | #!/usr/bin/env python    | <?                                |
| W |                         |                                    |                          |                                   |
|   | i=1                     | $i = 1;                            | i = 1                    | $i = 1 ;                          |
| H |                         |                                    |                          |                                   |
|   | while [ $i -le 10 ]; do | while ( $i <= 10 ){                | while i <= 10 :          | while ( $i <= 10 ){               |
| I |                         |                                    |                          |                                   |
|   |      echo $i            |        print "$i\n";               |       print i            |        echo "$i\n";               |
| L |      i=$((i+1))         |        $i++                        |       i=i+1              |        $i++ ;                     |
|   |                         |                                    |                          |                                   |
| E | done                    | }                                  |                          | }                                 |
|   |                         |                                    |                          |                                   |
|   |                         |                                    |                          | ?>                                |
+---+-------------------------+------------------------------------+--------------------------+-----------------------------------+

Sintaxes de 'for' e 'while' em bash puro:		Funcao Recursiva em Shell:

+---+-----------------------------+			+---+-------------------------------------------------------+
|   | #!/bin/bash                 |			|   | #!/bin/bash                                           |
| F |                             |			|   |                                                       |
|   | for ((i=0; i<=10; i++)); do |			| R | [ -z $1 ] && echo "$0:Erro:use $0 0 [numero]" && exit |
| O |                             |			|   |                                                       |
|   |       echo $i               |			| E | fat(){                                                |
| R |                             |			|   |                                                       |
|   | done                        |			| C | if [ $1 -ge 1 ]; then                                 |
|   |                             |			|   |                                                       |
+---+-----------------------------+			| U |     echo $(( `fat $(( $1 - 1 ))` * $1 ))              |
|   | #!/bin/bsh                  |			|   |                                                       |
| W |                             |			| R | else                                                  |
|   | i=1                         |			|   |                                                       |
| H |                             |			| S |     echo 1                                            |
|   | while (( i<=10 )); do       |			|   |                                                       |
| I |                             |			| A | fi                                                    |
|   |       echo $i               |			|   |                                                       |
| L |       i=$((i+1))            |			| O | }                                                     |
|   |                             |			|   |                                                       |
| E | done                        |			|   | echo `fat $1`                                         |
|   |                             |			|   |                                                       |
+---+-----------------------------+			+---+-------------------------------------------------------+