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Batch Files - Passing parameters |
Passing parameters between batch files and command line applications (scripted in PHP or Perl) is relatively easy. Passing parameters from the parent application to a child application, you can use either environment variables or include parameters in the command line that runs the application. Passing parameters from a child to a parent, either use an intermediary file or use the batch command "FOR /F" to process the output text from the child.
This page covers the above and provides examples that can be used in Uniform Server batch files.
Background
A parent process passes its environment to a child process. A child inherits only a copy (snapshot of the current environment) of the parent environment. This means a child cannot change the original environment.
Although a child process can access and change inherited environment variables, it requires a mechanism to pass any changes back to the parent. Writing new or modified variables to a file is one solution. A parent reads this file and makes changes as required.
An alternative is for the child to output variables to the standard stream (for example, "print" or "echo" uses the standard stream to output to the screen), allowing the parent to intercept and process this data. Although it may sound complicated, the command FOR /F has this functionality built in, hence is easy to implement.
Passing variables to a child
This example demonstrates passing by environment variables and program (application) parameters. Although only one environment variable and one program parameter is used in the demonstration, you are not limited to the number you can pass to an application.
In folder UniServerZ, create two new files named testp1.bat and testp1.php with the following content, replacing phpxx with the php version number selected on your system:
testp1.bat
@echo off rem ### working directory current folder pushd %~dp0 rem ### set variables set HOME=%cd% set US_ROOTF=%HOME% set US_ROOTF=%US_ROOTF:\=/% set US_PHP_EXE=%HOME%\core\phpxx\php.exe rem #------Test code ----------- rem ### Set environment variable var1 rem ### Run PHP script with parameter school2 echo Test A) set var1=school1 %US_PHP_EXE% -n -f testp1.php school2 rem #----End test code --------- rem ### restore original working directory popd pausetestp1.php
<?php
$a = getenv('var1'); // Get environment variable
print ($a . PHP_EOL); // Output this variable
$b = $argv[1]; // Get argument1
print ($b . PHP_EOL); // Output argument1
?>
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Comments
Code outside the two test lines are the reference template batch script. rem #------Test code ----------- rem #----End test code --------- A) The batch command "set var1=school1" sets the environment variable "var1" to value of "school1". The php script testp1.php is run with parameter "school2" Test
Note 1: The output from the PHP script is displayed but not captured, hence cannot be used in the batch file. This will be resolved later using FOR /F command. Note 2: The PHP script is relatively short and can be run directly as a one-liner from the batch file, removing the need for a script: Replace the following line: %US_PHP_EXE% -n -f testp1.php school2 With this line:
%US_PHP_EXE% -n -r "print(getenv('var1') . PHP_EOL . $argv[1] . PHP_EOL);" school2
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FOR /F overview
The FOR command has many options. Fortunately, only the "/F" option is required to extract variables/parameters from an application.
There are three command line formats for this option, as follows:
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Notes: |
token space delimited token more tokens,comma delimited,12Z 123=ABC,mixed#delimiters |
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filenameset is one or more file names. Each file is opened, read, and processed before going on to the next file in filenameset. Processing consists of reading the file one line at a time and then breaking the line up into individual items of data or 'tokens'. The DO command is then executed with the parameter(s) set to the token(s) found. By default, "/F" passes the first blank separated token from each line of each file. Blank lines are skipped. |
FOR /F ["options"] %%variable IN (filenameset) DO command [command-parameters] |
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LiteralString - A string of text will be treated just like a single line of input from a command. |
FOR /F ["options"] %%variable IN ("LiteralString") DO command [command-parameters]
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command - The named command along with any parameters is executed. Processing of a command consists of reading the output from the command one line at a time and then breaking the line up into individual items of data or 'tokens'. The DO command is then executed with the parameter(s) set to the token(s) found. |
FOR /F ["options"] %%variable IN ('command') DO command [command-parameters]
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You can override the default parsing behavior by specifying the optional "options" parameter. This is a quoted string that contains one or more keywords to specify different parsing options. The keywords are:
| Keyword | Description |
| eol=c | Specifies an end of line comment character (just one character) - default is ";" |
| skip=n | Specifies the number of lines to skip at the beginning of the file. |
| delims=xxx | Specifies a delimiter set. This replaces the default delimiter set of space and tab. |
| tokens=x,y,m-n | Specifies which tokens from each line are to be passed to the "for" body for each iteration. As a result, additional variable names are allocated. The "m-n" form is a range, specifying the mth through the nth tokens. If the last character in the "tokens=" string is an asterisk (*), an additional variable is allocated and receives the remaining text on the line after the last token that is parsed. |
| usebackq | Specifies that you can use quotation marks to quote file names in filenameset. A back quoted string is executed as a command, and a single quoted string is a literal string command. |
FOR /F Passing LiteralString
String processing for the three FOR /F command line formats filenameset, LiteralString and command are identical. This section provides examples using the LiteralString format, primarily because you can see the text is being processed and requires only a single file, making it easier to experiment with the format command options.
In folder UniServerZ create a new file named testp2.bat, replacing phpxx with the php version number selected on your system:
testp2.bat
@echo off
rem ### working directory current folder
pushd %~dp0
rem ### set variables
set HOME=%cd%
set US_ROOTF=%HOME%
set US_ROOTF=%US_ROOTF:\=/%
set US_PHP_EXE=%HOME%\core\phpxx\php.exe
rem #------Test code -----------
echo A) No token specified defaults to 1 hence only %%%%A assigned
echo FOR /F %%%%A IN ("123 456 xyz") DO echo Result: ..%%%%A..%%%%B..%%%%C..
echo Expected ..123..%%B..%%C..
FOR /F %%A IN ("123 456 xyz") DO echo Result: ..%%A..%%B..%%C..
echo.
echo B) Token 1 and 3 specified. Each match is assigned
echo the next letter in sequence starting from A then B etc.
echo note %%%%C is never assigned because only two tokens specified
echo FOR /F "tokens=1,3" %%%%A IN ("aaa bbb ccc") DO echo Result: ..%%%%A..%%%%B..%%%%C..
echo Expected ..aaa..ccc..%%C..
FOR /F "tokens=1,3" %%A IN ("aaa bbb ccc") DO echo Result: ..%%A..%%B..%%C..
echo.
echo C) Token 1-3 range specified. Each match is assigned
echo a letter in sequence starting from A then B then C.
echo FOR /F "tokens=1-3" %%%%A IN ("123 456 xyz") DO echo Result: ..%%%%A..%%%%B..%%%%C..
echo Expected ..123..456..xyz..
FOR /F "tokens=1-3" %%A IN ("123 456 xyz") DO echo Result: ..%%A..%%B..%%C..
echo.
echo D) Token 1-3 specified. Multi spaces are treated as a single space.
echo FOR /F "tokens=1-3" %%%%A IN ("123 456 xyz ") DO echo Result: ..%%%%A..%%%%B..%%%%C
echo Expected ..123..456..xyz..
FOR /F "tokens=1-3" %%A IN ("123 456 xyz ") DO echo Result: ..%%A..%%B..%%C..
echo.
echo E) Token 1-3 specified. delims specifies a comma and space
echo FOR /F "tokens=1-3 delims=, " %%%%A IN ("a,Z x") DO echo Result: ..%%%%A..%%%%B..%%%%C
echo Expected..a..Z..x..
FOR /F "tokens=1-3 delims=, " %%A IN ("a,Z x") DO echo Result: ..%%A..%%B..%%C..
echo.
echo F) Token 1* specified. 1 match first delim, then * match reset of line
echo FOR /F "tokens=1* delims=, " %%%%A IN ("s,z2 p") DO echo Result: ..%%%%A..%%B..%%%%C
echo Expected ..s..z2 p..%%C..
FOR /F "tokens=1* delims=, " %%A IN ("s,z2 p") DO echo Result: ..%%A..%%B..%%C..
echo.
echo G) Token 1* specified.
echo use an environment variable for the string.
set str=phpxx\php.exe
echo set str=\phpxx\php.exe
echo FOR /F "tokens=1* delims=\" %%A IN ("%str%") DO echo Result: ..%%A..%%B..
echo Expected ..phpxx..php.exe..
FOR /F "tokens=1-3 delims=\" %%A IN ("%str%") DO echo Result: ..%%A..%%B..
echo.
rem #----End test code ---------
rem ### restore original working directory
popd
pause
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Comments
Each test section A) to G) have the following structure:
Note 1: The echo format ..%%A..%%B..%%C.. outputs assigned variables %%A, %%B and %%C enclosed between two full stops on either side. These full stops are included for testing. Apart from visually separating the variables, they allow you to see any unexpected characters captured. Note 2: Variables in a FOR /F command require a starting character, for example %%A. From this starting point, additional letters are assigned in sequence as required by the FOR command. A variable is created for each token captured and assigned the token's value. If you specify a variable in the DO section that has not been created and assigned a value, its name is output instead. Note 3: The LiteralString format requires a string to be enclosed in quotes. You can use environment variables. Again, these must be enclosed in quotes. Note 4: In the ["options"] section, you can place the options in any order. However, it is recommended you place "delims" at the end because it makes specifying a space easier; for example "tokens=1* delims=, " Test
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FOR /F Passing filenameset -1
Extracting a single parameter as the first line of a file such as the MySQL password is achieved using either the SET command with redirection operator, or using the FOR /F command with filenameset format. For comparison, an example of both is shown. Folders (ssl and www) can be protected with allowed usernames and password pairs contained in a file. A user's password can be extracted with a FOR /F command.
In folder UniServerZ, create a new file named testp3.bat, replacing phpxx with the php version number selected on your system:
FOR /F Passing filenameset -2
This page is about passing parameters between scripts. For completeness, this section covers passing parameters using an intermediary file. The Uniform Server saves user configuration data to a file. This file can be considered an intermediary file. Data in this file is extracted using the FOR /F command with the filenameset format.
In folder UniServerZ, create a new file named testp4.bat, replacing phpxx with the php version number selected on your system:
FOR /F Passing command
The FOR /F with command format allows you to run a command line script and capture its output to memory. When the script terminates, memory content is read and is processed line-by-line. This allows you to pass parameters from a child process to the parent process. The following examples provide an introduction to its capability.
In folder UniServerZ, create a new file named testp5.bat:
Note: Generally, your PHP code would be run from a script (see PHP CLI for details). You would replace the following line:
'php.exe -n -r "print('name=fred'.PHP_EOL.'address=myspace');"'
with one of the following options:
'php test1.php' 'php -n test1.php' 'php -c core\phpxx\my_cli.ini test1.php'
Note: You must enclose the command in single quotes.
Perl passing parameters
Perl is another powerful scripting language that you can run as CLI from a batch file. For additional information, see Perl CLI page. Passing parameters is similar to PHP. This section provides an example using the above techniques to pass environment variables and parameters between a batch file and a Perl script.
Uniform Server is portable; it does not make any changes to a host PC configuration. This means the path to the Perl interpreter is undefined and must be added to the environment path before a Perl script is run from a batch file.
In folder UniServerZ, create two new files named testp6.bat and testp6.pl with the following content:
testp6.bat
@echo off rem ### working directory current folder pushd %~dp0 rem ### set variables set HOME=%cd% set PERL_PATH=%HOME%\core\perl\bin set PERL_EXE=%HOME%\core\perl\bin\perl.exe IF NOT EXIST %PERL_EXE% (echo Perl not installed! & goto END) set Path=%PERL_PATH%;%Path% rem #------Test code ----------- rem -- Set environment vars for Perl script set perl_var1=pvar1 set perl_var2=pvar2 rem -- run script with parameters rem -- display output from script perl testp6.pl pvar3 pvar4 echo. echo Script is run for second time however this run uses echo a FOR /F loop to extract and set variables perl_var1 and perl_var2 echo. FOR /F "tokens=1,2 delims==" %%A IN ( 'perl testp6.pl pvar3 pvar4' ) DO ( If %%A==perl_var1 Set perl_var1=%%B If %%A==perl_var2 Set perl_var2=%%B ) echo Display values that were updated by script: echo. echo perl_var1=%perl_var1% echo perl_var2=%perl_var2% echo. rem #----End test code --------- :END rem ### restore original working directory popd pausetestp6.pl
print "--------- Output from Perl script ----------\n";
print "Environment variable perl_var1 =".$ENV{"perl_var1"}."\n";
print "Environment variable perl_var2 =".$ENV{"perl_var2"}."\n";
print "Parameter 1 passed by commandline="."@ARGV[0]\n";
print "Parameter 2 passed by commandline="."@ARGV[1]\n";
print "Change and return Environment variables\n";
print "perl_var1=pvar1xxxxx\n";
print "perl_var2=pvar2zzzzz\n";
print "------- End output from Perl script ---------\n";
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Comments
Code outside the two test lines are the reference template batch script. rem #------Test code ----------- rem #----End test code --------- Common environment variables are initially set. set HOME=%cd% set PERL_PATH=%HOME%\core\perl\bin set PERL_EXE=%HOME%\core\perl\bin\perl.exe IF NOT EXIST %PERL_EXE% (echo Perl not installed! & goto END) set Path=%PERL_PATH%;%Path% If the Perl executable does not exist, it is assumed the Perl module has not been installed and an error message is displayed before exiting. If the executable exists, the path to Perl binaries is added to the environment path variable. Test code rem -- Set environment vars for Perl script set perl_var1=pvar1 set perl_var2=pvar2 The Perl script is run using the following line. Note: two parameters ("pvar3" and "pvar4") are passed on the command line. Raw output from the script is displayed. perl test6.pl pvar3 pvar4 A FOR /F loop runs the Perl script a second time. No output is displayed. Instead, output is captured and processed by the FOR /F loop, which extracts and sets the two variables "perl_var1" and "perl_var2". FOR /F "tokens=1,2 delims==" %%A IN ( 'perl test6.pl pvar3 pvar4' ) DO ( If %%A==perl_var1 Set perl_var1=%%B If %%A==perl_var2 Set perl_var2=%%B ) Finally, the two variables are displayed (echoed), allowing you to confirm variables have been changed. echo perl_var1=%perl_var1% echo perl_var2=%perl_var2% Test
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