I am writing a program which expects command line arguments of the form
-foo ${foo}
However, ${name} is Eclipse’s notation for variables. Passing the above command line argument causes Eclipse to look for an internal variable named foo and inserting that instead of the ${foo} variable specification before running the program.
What is the proper way of escaping ${foo} so Eclipse will pass it literally, rather than trying to expand it?
TL;DR: $\{foo}
The escape character for Eclipse is \; prepending this will cause Eclipse to pass the following character literally.
Of a string resembling a variable specification, only the opening brace needs to be escaped in order to pass the whole thing literally.
Escaping $ and } is not needed but will do no harm – $\{foo}, \$\{foo} and \$\{foo\} will all result in ${foo} being passed to the program.
Related
First, I'm in PowerShell and I've entered the doskey /exename=powershell.exe option.
Second, I did something that I now realize doesn't quite work:
doskey envpath=$env:Path -split ';'
The goal was to have it print the path environment variable (whatever it is at the time I later enter envpath). However, it seems to have evaluated $env:Path while defining the macro, so the macro now appears to be all the paths in my path environment variable followed by '-split ;'. So that's a problem, but only listed here for context. I'll figure that out separately. The purpose of this question (one question per post) is the following:
I was following this and getting something weird...
If I now enter doskey /macros:all I get:
"envpath=C:\WINDOWS\system32;C:\WINDOWS;<etc>;" -split ;
Please note the quotes.
Now, if, per the above-linked other answer, I enter doskey envpath=something (literally) then doskey /macros:all returns:
"envpath=C:\WINDOWS\system32;C:\WINDOWS;<etc>;" -split ;
envpath=something
(which is expected except for the quoted part).
And when I do doskey envpath= it clears/deletes that macro, and doskey /macros:all, returns the first result again.
So my question: What is this entry in the quotes and how do I get rid of that please?
Hopefully I've explained that clearly enough. If confused please feel free to ask for clarification. Thanks in advance for help!
As noted in the answer to your related question,
it's best to avoid use of doskey.exe in PowerShell, because getting it to work requires forgoing PowerShell's own, rich command-line editing experience, by unloading the PSReadLine module first (Remove-Module PSReadLine) - see this answer for background information.
the better alternative is to define a PowerShell function and add it to your $PROFILE file, as shown in the linked answer.
If you want to use doskey.exe nonetheless, define your macro as follows (for PowerShell (Core) 7+, replace powershell.exe with pwsh.exe):
doskey /exename=powershell.exe envpath = `$env:Path -split "';'"
The tokens that make up the PowerShell command must be passed as individual arguments to doskey.exe, and be sure to follow the = with a space.
If you accidentally pass the PowerShell command as a single, quoted argument, doskey.exe stores enclosing "..." as part of the macro and includes these quotes when it expands the macro.
If you additionally also include the macro name in that single, quoted argument, you not only get a virtually unusable macro,[1] you also cannot remove it in-session (neither individually, with doskey /exename=powershell.exe envpath=, nor as part of clearing all macros with Alt-F10) - you must start a new PowerShell session to get rid of it.
Note that the macro name is also included if you attempt partial quoting in PowerShell, e.g., doskey envpath="`$env:Path -split ','" is effectively the same as doskey "envpath=`$env:Path -split ','", due to how PowerShell rebuilds the command line behind the scenes (see below).
To avoid instant expansion of $env:Path, the $ character is preceded by PowerShell's escape character, the so-called backtick (`).
To preserve the '...'-quoting around ;, outer "..." quoting is used.
This is necessary, because PowerShell rebuilds the command line behind the scenes when it invokes external programs, which involves translating '...' quoting into "..." quoting if necessary; that is, irrespective of what quoting was originally used on the PowerShell side, an argument is enclosed in "..." if it contains spaces and used unquoted otherwise; thus, ';' by itself would turn into just ; on the behind-the-scenes command line; an originally partially quoted argument that contains spaces ends up being double-quoted as a whole.
[1] In a macro definition that doskey /macros or doskey /macros:all lists as "envpath=C:\WINDOWS\system32;C:\WINDOWS;<etc>;" -split ;, the macro name is "envpath verbatim, i.e. including the opening ". The - then unbalanced - closing " is retained in the text to expanded to.
I'm having a problem moving forward through a path with PowerShell. I am able to move up the directory but not down. Here's the situation:
I open PowerShell and type in the "pwd" command and it shows that I am currently in PS C:\Users\Robert Inspiron14>
I type the command "cd.." and now I move to PS C:\Users>
I then attempt to change directories by typing: "cd C:\Users\Robert Inspiron14" and I am unable to. Unfortunately, I can't post a picture yet due to lack of reputation.
I'm able to perform the change in CMD but not PowerShell. Also, I don't know how to change the User from "Robert Inspiron14" to just "Robert". Any help is appreciated!
Before PowerShell can execute your cd command, it needs to parse it, and PowerShell's parser interprets your command like this:
cd C:\Users\Robert Inspiron14
\/ \_____________/ \________/
Command Name | |
argument 1 |
argument 2
In other words, C:\Users\Robert and Inspiron14 are interpreted as separate arguments.
Neither argument is a path to a valid directory, so cd (or rather Set-Location for which cd is an alias) throws an error.
You can force PowerShell to recognize C:\Users\Robert Inspiron14 as a single string argument by qualifying its boundaries using quotation marks (both " and ' will work):
cd 'C:\Users\Robert Inspiron14'
You can read more about how PowerShell parses command expressions in the about_Parsing help topic
To complement Mathias R. Jessen's helpful answer with more background information:
Quoting an argument that contains spaces is a general syntactic necessity, in all shells, because unquoted spaces are used to separate multiple arguments.
It isn't only spaces that require quoting, but any of PowerShell's so-called metacharacters (characters that, when used unquoted, have syntactic function); for instance, passing the path to a directory literally named a;b requires quoting as well, given that ; would otherwise be interpreted as a statement separator.
There are multiple quoting styles:
Since your path value is a literal - it contains no variable references or expressions - a verbatim (single-quoted) string ('...') is the best choice.
cd 'C:\Users\Robert Inspiron14'
If your path contains variables or subexpressions, you must use an expandable (double-quoted) string ("...")[1]
cd "$HOME\Documents"
Another, less common solution is to individually escape the space characters with `, the so-called backtick, PowerShell's escape character:
cd C:\Users\Robert` Inspiron14
Also note:
PowerShell's tab-completion automatically applies quoting as necessary.
cd.. is the name of a built-in function in PowerShell, whose sole purpose is to emulate cmd.exe's (questionably permissive) behavior (see below); the function performs a syntactically correct Set-Location .. call (verify by executing ${function:cd..}), with a space separating the command name from its argument.
Contrast with cmd.exe:
Unfortunately, cmd.exe's built-in cd command decided not to enforce its usual syntax rules, and enabled calls such as cd C:\Program Files.
It should never have done that: While convenient at first glance, it constitutes a problematic exception from the usual rules that invites confusion.
Note that cmd.exe's tab completion properly quotes arguments that contain spaces.
Similarly, cd.. was unfortunately allowed as as syntactically exceptional alternative to the correct cd .. - see the comments on this answer for details.
[1] Note "..."-quoting isn't strictly necessary if you use variable references in a path, as long as any literal components do not require quoting; e.g., $HOME\foo is fine without quoting, whereas the " around "$HOME\foo bar" are required. With subexpressions ($(...)), the rules get more complicated, so the simplest approach is to always use "..."-quoting with them.
My PowerShell script has one parameter. It is invoked by a tool, which feeds it the argument. The argument contains special characters such as ', " and %. With special characters, PowerShell expects the argument to be surrounded by single or double quotes. What if the argument contains both single and double quotes? No problem. If the argument is surrounded by single quotes, use two single quotes instead of one inside the argument. If it surrounded by double quotes, use two double quotes instead of one inside the argument.
Problem: I cannot modify the argument before passing it to the script, i.e., I cannot double the single/double quotes in the argument. Is there anything I can do?
-Rohan.
EDIT #1:
Reason I cannot modify the argument is that it is automatically passed to the script by the tool.
EDIT #2:
The argument is a password and so, I need to accept and store it as a secure string in the script.
One option is to pass it as a base64-encoded string, and then decode it in the script:
Using Powershell -encodedcommand to pass parameters
I'm working on a Perl script that I was hoping to capture a string entered on the command line without having to enter the quotes (similiar to bash's "$#" ability). I'll be using this command quite a bit so I was hoping that this is possible. If I have:
if ($ARGV) {
I have to put the command line string in quotes. I'd rather do the command something like this:
htmlencode some & HTML <> entities
Without the quotes. Is there a way to do this in Perl?
The #ARGV array contains the arguments to the Perl script - no quotes needed.
That said, the question asks about:
I have to put the command line string in quotes. I'd rather do the command something like this:
htmlencode some & HTML <> entities
Without the quotes. Is there a way to do this in perl?
Well, if the command shown is written at the shell command line, you have to obey shell conventions - which means escaping the '&' and '<>' to prevent the shell from interpreting them. Likewise, within a Perl script, that sequence would need to be protected from Perl. Maybe you'd write:
system "htmlencode", "some", "&", "HTML", "<>", "entities";
That is, everything would have to be in quotes - but that notation would avoid executing the shell and having the shell interpret the commands.
Alternatively again, if you put the arguments into an array (with quotes at the time the array is loaded), then you could pass that array to system and not use any quotes:
my #args = ( "htmlencode", "some", "&", "HTML", "<>", "entities" );
system #args;
But I think the question is confused.
You put quotes around $# in bash so that it expands to have each element in the array quoted. The reason to do that is so that each element of the array continues to be treated as a single argument when you pass them all to the next command.
The analogue to that in Perl is when you want to pass those parameters to another external command. If you're running the external program with the backtick operators, then you'd need to quote each parameter, but if you use system, then Perl will take care of keeping all the parameters separate for you.
In fact, separate parameters are the way programs are executed on Unix anyway. The single-string command-line format is there because we need to be able to type things at the command prompt. Like all shells, bash has special rules about how to split that single string into multiple arguments. But if you already have them separated in a Perl array, don't put them back into a single string. Keep them separate.
I want to call a perl script from powershell where a parameter is quoted:
myProg -root="my path with spaces"
I've tried to use -root='"my path with spaces"', -root='my path with spaces', -root=\"my path with spaces\", but nothing seems to work. After pressing <ENTER>, I see >> as a prompt.
How do I pass this quoted argument on the command line in Powershell?
Try putting the entire argument in quotes and escape the inner quotes, that way powershell won't try to parse it:
myProg '-root=\"my path with spaces\"'
It may be useful to explicitly denote each command-line argument. Instead of relying on the parser to figure out what the arguments are via whitespace, you explicitly create an array of strings, one item for each command-line argument.
$cmdArgs = #( `
'-root="my path with spaces"', `
'etc', `
'etc')
& "C:\etc\myprog.exe" $cmdArgs
I solved a similar issue with
Invoke-Expression '&.\myProg.exe `-u:IMP `-p: `-s:"my path with spaces"'
Hope this helps.
I ran into a similar issue when trying to use powershell to pass arguments with spaces to an executable. In the end I found that I could get a quoted parameter passed by triple-escaping the closing double quote of the argument when using Invoke-Expression:
iex "&`"C:\Program Files\Vendor\program.exe`" -i -pkg=`"Super Upgrade```" -usr=User -pwd=password2"
What isn't apparent is why I can use a single back-tick character to escape the executable while I have to use 3 back-ticks to finish off a quoted parameter. All I know is that this is the only solution that worked for me.