Root user/sudo equivalent in Cygwin?

Question

I\'m trying to run a bash script in Cygwin.

I get Must run as root, i.e. sudo ./scriptname errors.

chmod 777 scriptname does no

Answer 1

It seems that cygstart/runas does not properly handle "$@" and thus commands that have arguments containing spaces (and perhaps other shell meta-characters -- I didn't check) will not work correctly.

I decided to just write a small sudo script that works by writing a temporary script that does the parameters correctly.

#! /bin/bash

# If already admin, just run the command in-line.
# This works on my Win10 machine; dunno about others.
if id -G | grep -q ' 544 '; then
   "$@"
   exit $?
fi

# cygstart/runas doesn't handle arguments with spaces correctly so create
# a script that will do so properly.
tmpfile=$(mktemp /tmp/sudo.XXXXXX)
echo "#! /bin/bash" >>$tmpfile
echo "export PATH=\"$PATH\"" >>$tmpfile
echo "$1 \\" >>$tmpfile
shift
for arg in "$@"; do
  qarg=`echo "$arg" | sed -e "s/'/'\\\\\''/g"`
  echo "  '$qarg' \\" >>$tmpfile
done
echo >>$tmpfile

# cygstart opens a new window which vanishes as soon as the command is complete.
# Give the user a chance to see the output.
echo "echo -ne '\n$0: press <enter> to close window... '" >>$tmpfile
echo "read enter" >>$tmpfile

# Clean up after ourselves.
echo "rm -f $tmpfile" >>$tmpfile

# Do it as Administrator.
cygstart --action=runas /bin/bash $tmpfile

Answer 2

I landed here through google, and I actually believe I've found a way to gain a fully functioning root promt in cygwin.

Here are my steps.

First you need to rename the Windows Administrator account to "root" Do this by opening start manu and typing "gpedit.msc"

Edit the entry under Local Computer Policy > Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options > Accounts: Rename administrator account

Then you'll have to enable the account if it isn't yet enabled. Local Computer Policy > Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options > Accounts: Administrator account status

Now log out and log into the root account.

Now set an environment variable for cygwin. To do that the easy way: Right Click My Computer > Properties

Click (on the left sidebar) "Advanced system settings"

Near the bottom click the "Enviroment Variables" button

Under "System Variables" click the "New..." button

For the name put "cygwin" without the quotes. For the value, enter in your cygwin root directory. ( Mine was C:\cygwin )

Press OK and close all of that to get back to the desktop.

Open a Cygwin terminal (cygwin.bat)

Edit the file /etc/passwd and change the line

Administrator:unused:500:503:U-MACHINE\Administrator,S-1-5-21-12345678-1234567890-1234567890-500:/home/Administrator:/bin/bash

To this (your numbers, and machine name will be different, just make sure you change the highlighted numbers to 0!)

root:unused:0:0:U-MACHINE\root,S-1-5-21-12345678-1234567890-1234567890-0:/root:/bin/bash

Now that all that is finished, this next bit will make the "su" command work. (Not perfectly, but it will function enough to use. I don't think scripts will function correctly, but hey, you got this far, maybe you can find the way. And please share)

Run this command in cygwin to finalize the deal.

mv /bin/su.exe /bin/_su.exe_backup
cat > /bin/su.bat << "EOF"
@ECHO OFF
RUNAS /savecred /user:root %cygwin%\cygwin.bat
EOF
ln -s /bin/su.bat /bin/su
echo ''
echo 'All finished'

Log out of the root account and back into your normal windows user account.

After all of that, run the new "su.bat" manually by double clicking it in explorer. Enter in your password and go ahead and close the window.

Now try running the su command from cygwin and see if everything worked out alright.

Answer 3

Building on dotancohen's answer I'm using an alias:

alias sudo="cygstart --action=runas"

Works as a charm:

sudo chown User:Group <file>

And if you have SysInternals installed you can even start a command shell as the system user very easily

sudo psexec -i -s -d cmd

Answer 4

I met this discussion looking for some details on the sudo implementation in different operating systems. Reading it I found that the solution by @brian-white (https://stackoverflow.com/a/42956057/3627676) is useful but can be improved slightly. I avoided creating the temporary file and implemented to execute everything by the single script.

Also I investigated the next step of the improvement to output within the single window/console. Unfortunately, without any success. I tried to use named pipes to capture STDOUT/STDERR and print in the main window. But child process didn't write to named pipes. However writing to a regular file works well.

I dropped any attempts to find the root cause and left the current solution as is. Hope my post can be useful as well.

Improvements:

• no temporary file
• no parsing and reconstructing the command line options
• wait the elevated command
• use mintty or bash, if the first one not found
• return the command exit code

    #!/bin/bash

    # Being Administrators, invoke the command directly
    id -G | grep -qw 544 && {
        "$@"
        exit $?
    }

    # The CYG_SUDO variable is used to control the command invocation
    [ -z "$CYG_SUDO" ] && {
        mintty="$( which mintty 2>/dev/null )"
        export CYG_SUDO="$$"
        cygstart --wait --action=runas $mintty /bin/bash "$0" "$@"
        exit $?
    }

    # Now we are able to:
    # -- launch the command
    # -- display the message
    # -- return the exit code
    "$@"
    RETVAL=$?

    echo "$0: Press  to close window..."
    read

    exit $RETVAL

Answer 5

Or install syswin package, which includes a port of su for cygwin: http://sourceforge.net/p/manufacture/wiki/syswin-su/

Answer 6

What I usually do is have a registry "Open Here" helper in order to open a cygwin shell with administrative privileges quite easy from anywhere in my computer.

Be aware you have to have the cygwin "chere" package installed, use "chere -i -m" from an elevated cygwin shell first.

Assuming your cygwin installation is in C:\cygwin...

Here's the registry code:

Windows Registry Editor Version 5.00

[-HKEY_CLASSES_ROOT\Directory\shell\cygwin_bash]

[HKEY_CLASSES_ROOT\Directory\shell\cygwin_bash]
@="Open Cygwin Here as Root"
"HasLUAShield"=""

[HKEY_CLASSES_ROOT\Directory\shell\cygwin_bash\command]
@="c:\\cygwin\\bin\\mintty.exe -i /Cygwin-Terminal.ico -e /bin/xhere /bin/bash.exe"

[-HKEY_CLASSES_ROOT\Directory\Background\shell\cygwin_bash]

[HKEY_CLASSES_ROOT\Directory\Background\shell\cygwin_bash]
@="Open Cygwin Here as Root"
"HasLUAShield"=""

[HKEY_CLASSES_ROOT\Directory\Background\shell\cygwin_bash\command]
@="c:\\cygwin\\bin\\mintty.exe -i /Cygwin-Terminal.ico -e /bin/xhere /bin/bash.exe"

[-HKEY_CLASSES_ROOT\Drive\shell\cygwin_bash]

[HKEY_CLASSES_ROOT\Drive\shell\cygwin_bash]
@="Open Cygwin Here as Root"
"HasLUAShield"=""

[HKEY_CLASSES_ROOT\Drive\shell\cygwin_bash\command]
@="c:\\cygwin\\bin\\mintty.exe -i /Cygwin-Terminal.ico -e /bin/xhere /bin/bash.exe"

Hope this helps. Let me know if it works for you. Thanks.

PS: You can grab this code, copy and paste it and save it in a name.reg file to run it... or you can manually add the values.