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fancy_scripts

Fancy scripts for text processing, web development and more

The set of scripts, which reveals the power of regular expressions and/or POSIX shell (bash):

  • html2csv.bat - batch file, which converts html tables from html file to csv file (Windows, cmd.exe, sed.exe);

  • html2csv.sh - shell script, which converts html tables from html file to csv file (Linux, Mac OS X, Unix, Android, bash, sed);

  • hyphwords.sh - shell script, which produces hyphenation of monospace text by words (Linux, Mac OS X, Unix, Android, Windows, bash, sed);

  • bash-cgi.sh - CGI (Common Gateway Interface) HTTP(S) server shell script, which processes :

    • the query string into the $QUERY_STRING_GET key and value array;
    • the post request's data as is into the $POST_STRING;
    • the post request's data (x-www-form-urlencoded) into the $QUERY_STRING_POST key and value array, but it can be disabled with the assignment QUERY_STRING_POST=false before including this script;
    • the cookies data into the $HTTP_COOKIES key and value array.

    Demands bash version 4.0 or higher (to define the key and value arrays above).

    All processing is made by bash only (i.e. in an one process) without any external dependencies and additional processes invoking.

    It has:

    • the check for max length of data, which can be transferred to it's input, as well as processed as query string and cookies;
    • the redirect() procedure to produce redirect to itself with the extension changed to .html (it is useful for an one page's sites);
    • the http_header_tail() procedure to output the last two strings of the HTTP(S) respond's header;
    • the $REMOTE_ADDR value sanitizer from possible injections;
    • the parser and evaluator of the escaped UTF-8 symbols embedded into the values passed to the $QUERY_STRING_GET, $QUERY_STRING_POST and $HTTP_COOKIES;
    • the sanitizer of the $QUERY_STRING_GET, $QUERY_STRING_POST and $HTTP_COOKIES values against possible SQL injections (the escaping like the mysql_real_escape_string php function does, plus the escaping of @ and $).

    As it is the server script it can't be invoked in terminal and should be run in the server's CGI environment.

    In the server's CGI environment it has such global variables related to the current web request:

    • $CONTENT_LENGTH
    • $QUERY_STRING
    • $HTTP_COOKIE
    • $REMOTE_ADDR
    • $HTTP_USER_AGENT

    The web request's body (POST data) is transferred to the script's input.

    It can be included into another web bash script using a dot or the source command.

    Programming for web using bash one need to remember about possible bash injections in an use input:

    • asterisk;
    • semicolon in the loops over a parameters list, taken from an user input;
    • eval of an user input, which is dangerous by itself, but also removes escapes from the dengerous symbols, when is used with parameters, which is not wrapped into the single quotes.

    Thus to output a valid HTML page one need just to create such bash script with LF line endings and 0750 file permission:

      #!/bin/bash
  # Import bash-cgi.sh
  source ${0%/*}/bash-cgi.sh
  # The bash CGI script, which increments the cookies value on each request
  cookie_value=${HTTP_COOKIES[Hello_World]}
  let cookie_value+=1
  echo -e "Set-Cookie: Hello_World=$cookie_value; SameSite=None; Secure\r"
  http_header_tail
  echo -n "
  <!DOCTYPE html>
  <html lang='en'>
  <head>
  <meta charset='UTF-8'>
  <title>bash-cgi-test.sh Demo</title>
  </head>
  <body>
    Hello_World cookie value == $cookie_value
  </body>
  </html>
  "

    Example may be available here