I know how to add values to the path variable, so my question is not how to use it.
Rather, I want to know how it works under the hood. When you type in the name of a program to execute, how does the system make use of PATH to find the matching program? How does it know when it finds a match?
for example...
when you set c:\python27\ into your environment path...
and you goto cmd, you are at c:\ and you type python
cmd knows to check the environment path which it will find c:\python27\ among others. then it looks for the command in each path listed in your environment paths
then executes the command if it finds it
simply the env path tells where to look for the command if it is not in the current directory
I thought for sure there would be an SO question on this, but I haven't been able to find one.
I have 2 SQL files, myFile1.sql and myFile2.sql. myFile1.sql calls myFile2.sql like so:
-- In myFile1.sql:
#scripts/myFile2
This works with no problem, but now I'd like to pass an argument to the file. I've tried doing the following, with no success (results in a File Not Found exception):
#scripts/myFile2 'ImAnArgument'
Does anyone know what the syntax would be to do this?
I'm guessing your problem is that scripts/myFile2.sql is a relative path from the script it is located in. If that is so, then it is following that path from the directory where SQL*Plus was started (the current working directory). If this is the problem, then it's not the parameter that is the issue, but rather that SQL*Plus can't find the file. In this case, you should use ##, which invokes the path relative to the file it's located in.
The parameter should work just as you proposed (documentation). Parameters provided when invoking a file are placed into substitution variables (rather than bind variables) and can be referenced by using an ampersand followed by the argument number. In your example, 'ImAnArgument' would be &1.
After many attempts, I wasn't able to pass a parameter in (and I still don't understand why not). But here is what I did to get the same affect:
-- In myFile1.sql:
DEFINE my_arg = 'ImAnArgument';
#scripts/myFile2
Then
-- In myFile2.sql
-- Do stuff using the variable my_arg, such as
SELECT my_arg FROM my_table;
I need to know some basic information on the for command in batch scripts. One thing I want to know is why its %%variable instead of %variable%.
%A is for use on command lines only.
%%A is used when used in batch files.
The single-percent %a syntax indicates a local variable within a batch file.
The percent-bracketed %foo% represents the value of an environment variable named foo.
From ss64.com:
If you are using the FOR command at the command line rather than in a batch program, specify %parameter instead of %%parameter
So %%param is for batch scripts and %param is for live commands. Greg is right, %param% is a different kind of variable. The "variable" in the FOR command exists only that scope, while environment %variables% persist in a wider scope.
I'm working on a script that processes a folder and there is always one file in it I need to rename. The new name should be the parent directory name. How do I get this in a batch file? The full path to the dir is known.
It is not very clear how the script is supposed to become acquainted with the path in question, but the following example should at least give you an idea of how to proceed:
FOR %%D IN ("%CD%") DO SET "DirName=%%~nxD"
ECHO %DirName%
This script gets the path from the CD variable and extracts the name only from it to DirName.
You can use basename command:
FULLPATH=/the/full/path/is/known
JUSTTHENAME=$(basename "$FULLPATH")
You can use built-in bash tricks:
FULLPATH=/the/full/path/is/known
JUSTTHENAME=${FULLPATH##*/}
Explanations:
first # means 'remove the pattern from the begining'
second # means 'remove the longer possible pattern'
*/ is the pattern
Using built-in bash avoid to call an external command (i.e. basename) therefore this optimises you script. However the script is less portable.
I am trying to set up some path using environment variable.
I added an environment variable "MAVEN_HOME" with the value "C:\maven".
Then in the path I added "%MAVEN_HOME%\bin;...rest".
When I type "echo $MAVEN_HOME%" I get the correct "C:\maven" printed on the screen.
But when I type "mvn" which is a batch file in the "bin" directory, it can't find it.
So, I manually added the entire path in PATH.
"C:\maven\bin;...rest"
and it was able to find "mvn" and execute it.
Could someone help me what I did wrong?
Check if there is a space character between the previous path and the next:
Incorrect:
c:\path1; c:\Maven\bin\; c:\path2\
Correct:
c:\path1;c:\Maven\bin\;c:\path2\
I had exactly the same problem, to solve it, you can do one of two things:
Put all variables in System Variables instead of User and add the ones you want to PATH
Or
Put all variables in User Variables, and create or edit the PATH variables in User Variable, not In System. The Path variables in System don't expand the User Variables.
If the above are all correct, but the problem is still present, you need to check the system Registry, in HKEY_CURRENT_USER\Environment, to make sure the "PATH" key type is REG_EXPAND_SZ (not REG_SZ).
My issue turned out to be embarrassingly simple:
Restart command prompt and the new variables should update
Things like having %PATH% or spaces between items in your path will break it. Be warned.
Yes, windows paths that include spaces will cause errors. For example an application added this to the front of the system %PATH% variable definition:
C:\Program Files (x86)\WebEx\Productivity Tools;C:\Sybase\IQ-16_0\Bin64;
which caused all of the paths in %PATH% to not be set in the cmd window.
My solution is to demarcate the extended path variable in double quotes where needed:
"C:\Program Files (x86)\WebEx\Productivity Tools";C:\Sybase\IQ-16_0\Bin64;
The spaces are therefore ignored and the full path variable is parsed properly.
%M2% and %JAVA_HOME% need to be added to a PATH variable in the USER variables, not the SYSTEM variables.
If there is any error at all in the PATH windows will silently disregard it. Things like having %PATH% or spaces between items in your path will break it. Be warned
Also worth making sure you're using the command prompt as an administrator - the system lock on my work machine meant that the standard cmd just reported mvn could not be found when typing
mvn --version
To use click 'start > all programs > accessories', right-click on 'command prompt' and select 'run as administrator'.
To address this problem, I have used setx command which try to set user level variables.
I used below...
setx JAVA_HOME "C:\Program Files\Java\jdk1.8.0_92"
setx PATH %JAVA_HOME%\bin
NOTE: Windows try to append provided variable value to existing variable value. So no need to give extra %PATH%... something like %JAVA_HOME%\bin;%PATH%
If the PATH value would be too long after your user's PATH variable has been concatenated onto the environment PATH variable, Windows will silently fail to concatenate the user PATH variable.
This can easily happen after new software is installed and adds something to PATH, thereby breaking existing installed software. Windows fail!
The best fix is to edit one of the PATH variables in the Control Panel and remove entries you don't need. Then open a new CMD window and see if all entries are shown in "echo %PATH%".
I had this problem in Windows 10 and it seemed to be solved after I closed "explorer.exe" in the Task Manager.
In my Windows 7.
// not working for me
D:\php\php-7.2.6-nts\php.exe
// works fine
D:\php\php-7.2.6-nts
I had the same problem, I fixed it by removing PATHEXT from user variable. It must only exist in System variable with .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC
Also remove the variable from user to system and only include that path on user variable
Copy the value of path to notepad and check if this corresponds with the echo %path% in terminal window and make changes if needed. Then delete the old path value and paste the notepad value back in.
I assume some invisible character entered there by some installation corrupted the path value.
Make sure both your System and User paths are set correctly.