# How to end up with a single backslash **URL:** \ **Category:** Get Help\ **Tags:** windows\ **Created:** [February 20, 2025, 6:52pm UTC](https://forum.ansible.com/t/how-to-end-up-with-a-single-backslash/40408 "2025-02-20T18:52:23Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![opoplawski](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/opoplawski/32/2112_2.png) [@opoplawski](https://forum.ansible.com/u/opoplawski)\ **Post date:** [February 20, 2025, 6:52pm UTC](https://forum.ansible.com/t/how-to-end-up-with-a-single-backslash/40408/1 "2025-02-20T18:52:23Z")
I need to select registry keys that match a regex, and then reconstruct the key paths. I’m trying to do: ```auto - name: Get registry entries ansible.windows.win_reg_stat: path: 'HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall' register: uninstall - set_fact: keys: | {{ ['HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall'] | product(uninstall.sub_keys | select('search', '^(nbi|BeyondTrust Remote Support Jump Client)')) | map('join', '\\') }} ``` This ends up with: ```auto "keys": [ "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\\\BeyondTrust Remote Support Jump Client [nwra.beyondtrustcloud.com-62F2CDFD]", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\\\nbi-glassfish-mod-4.1.1.0.1", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\\\nbi-nb-all-21.0.0.240215.0", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\\\nbi-nb-all-22.0.0.240522.0", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\\\nbi-nb-all-23.0.0.240913.0", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\\\nbi-nb-base-8.2.0.0.201609300101" ] ``` If I change the map to `'\'` I get: ```auto The full traceback is: Traceback (most recent call last): File "/usr/lib/python3.9/site-packages/ansible/executor/task_executor.py", line 505, in _execute self._task.post_validate(templar=templar) File "/usr/lib/python3.9/site-packages/ansible/playbook/task.py", line 291, in post_validate super(Task, self).post_validate(templar) File "/usr/lib/python3.9/site-packages/ansible/playbook/base.py", line 541, in post_validate value = method(attribute, getattr(self, name), templar) File "/usr/lib/python3.9/site-packages/ansible/playbook/task.py", line 299, in _post_validate_args args = templar.template(value) File "/usr/lib/python3.9/site-packages/ansible/template/ __init__.py", line 764, in template d[k] = self.template( File "/usr/lib/python3.9/site-packages/ansible/template/ __init__.py", line 738, in template result = self.do_template( File "/usr/lib/python3.9/site-packages/ansible/template/ __init__.py", line 963, in do_template data = _escape_backslashes(data, myenv) File "/usr/lib/python3.9/site-packages/ansible/template/ __init__.py", line 138, in _escape_backslashes for token in jinja_env.lex(d2): File "/usr/lib/python3.9/site-packages/ansible/_vendor/jinja2/lexer.py", line 864, in tokeniter raise TemplateSyntaxError( jinja2.exceptions.TemplateSyntaxError: unexpected char "'" at 177 line 1 fatal: [mark03.ad.nwra.com]: FAILED! => { "changed": false } ``` Similar if I add a \ to the end of the initial string path. ---
**Author:** ![sivel](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/sivel/32/1198_2.png) [@sivel](https://forum.ansible.com/u/sivel)\ **Post date:** [February 20, 2025, 8:20pm UTC](https://forum.ansible.com/t/how-to-end-up-with-a-single-backslash/40408/2 "2025-02-20T20:20:49Z")
This is all a bit complicated to explain. But I’ll give it a try: 1. In the normal callback output, you will not see a single `\` represented, because JSON requires that it be escaped, so internally a single `\` will always show up in JSON output as `\\`. So from that perspective you are ok. 2. When using single quotes in YAML around value, it is treated as the equivalent of a raw string in python, and in YAML it means you don’t have to escape a single `\` when writing it. More info at [YAML Ain’t Markup Language (YAML™) revision 1.2.2](https://yaml.org/spec/1.2.2/#73-flow-scalar-styles) 3. Folded or block scalars, as well as unquoted lines act like single quoted lines 4. If using double quotes you would need to type `\\` to represent a single `\`, because it requires escaping So, with the above in mind, you don’t want to use `map('join', '\\')` you would only use `'\'` in your specific example. ```yaml - set_fact: keys: | {{ ['HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall'] | product(uninstall.sub_keys | select('search', '^(nbi|BeyondTrust Remote Support Jump Client)')) | map('join', '\\') }} ``` This is because block scalars or those specified with `|` in YAML are treated like the docs call out for single quotes string values. So using `\\` in that format, is a literal double slash, and not an escaped slash If you were to use double quotes, then you would need `\\`: ```yaml - set_fact: keys: "{{ ['HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall'] | product(uninstall.sub_keys | select('search', '^(nbi|BeyondTrust Remote Support Jump Client)')) | map('join', '\\') }}" ``` And as I mention above, seeing `\\` in the ansible output, is normal, and actually represents an underlying string with only a single `\`, due to serialization requirements. ```json [ "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\BeyondTrust Remote Support Jump Client [nwra.beyondtrustcloud.com-62F2CDFD]", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\nbi-glassfish-mod-4.1.1.0.1", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\nbi-nb-all-21.0.0.240215.0", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\nbi-nb-all-22.0.0.240522.0", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\nbi-nb-all-23.0.0.240913.0", "HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\nbi-nb-base-8.2.0.0.201609300101" ] ``` I should also note, that when building a jinja2 template in a template file itself, and not as part of a YAML value, that everything I talked about from YAML formatting above doesn’t apply. So in a `whatever.j2` file, you would need to use `'\\'` to represent a single escaped `\`. So yeah, kinda complicated. Also just a note, if you did something like: ```yaml foo: "\bar" ``` That would parse, but would not represent a literal `\bar`, it would instead be treated as a python escape sequence for `\b` which is hex `0X08` for the `BEL` ascii character. ---
**Author:** ![opoplawski](https://sea1.discourse-cdn.com/ansible/user_avatar/forum.ansible.com/opoplawski/32/2112_2.png) [@opoplawski](https://forum.ansible.com/u/opoplawski)\ **Post date:** [February 21, 2025, 3:30pm UTC](https://forum.ansible.com/t/how-to-end-up-with-a-single-backslash/40408/3 "2025-02-21T15:30:30Z")
Thanks, but I think I understood most of that already, and it doesn’t seem like any of the suggested options work. The first version is the same as my first one and ends up with a double backslash between the base path and the key item: `Uninstall\\\\BeyondTrust`. If I try the double-quote version I get: ```auto ERROR! We were unable to read either as JSON nor YAML, these are the errors we got from each: JSON: Expecting value: line 1 column 1 (char 0) Syntax Error while loading YAML. found unknown escape character The error appears to be in '/home/orion-admin/ansible-nwra/playbooks-windows/fix-registry-uninstall.yml': line 13, column 26, but may be elsewhere in the file depending on the exact syntax problem. The offending line appears to be: - set_fact: keys: "{{ ['HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall'] | product(uninstall.sub_keys | select('search', '^(nbi|BeyondTrust Remote Support Jump Client)')) | map('join', '\\') }}" ^ here ``` So then I try: ```auto keys: "{{ ['HKLM:\\SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall'] | product(uninstall.sub_keys | select('search', '^(nbi|BeyondTrust Remote Support Jump Client)')) | map('join', '\\') }}" ``` and get: ```auto jinja2.exceptions.TemplateSyntaxError: unexpected char "'" at 177 line 1 ``` I ended up going with this: ```auto vars: backslash: \ ... keys: | {{ ['HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall'] | product(uninstall.sub_keys | select('search', '^(nbi|BeyondTrust Remote Support Jump Client)')) | map('join', backslash) }} ```