Parsia's Den

Because no one wants to be the other guy from Wham!

Cheat Sheet

Feb 24, 2016 - 5 minute read - cheatsheet

Often I need to do something that I have done many times in the past but I have forgotten how to do it. This is a page (or a series of pages if it grows large enough) to give me a simple repository of how-tos that I can access online. In this page you may find those commands and tips that I need from time to time (and usually forget when I need them).


Tar

Compressing a directory using tar
tar -zcvf target_tar.tar.gz directory_to_be_compressed

Decompressing a tar.gz file
tar -zcvf target_tar.tar.gz path/to/decompress/


OpenSSL

Dumping the TLS certificate using OpenSSL
echo | openssl s_client -connect HOST:PORT 2>/dev/null | openssl x509 -text -noout

TLS connection with a specific ciphersuite using OpenSSL
openssl s_client -connect HOST:PORT -cipher cipher-name -brief

  • -brief: reduced output
  • cipher-name: A cipher from output of openssl ciphers command

Amazon S3

Synching a folder with an Amazon S3 bucket using s3cmd
python s3cmd sync --acl-public --delete-removed --rr directory-to-sync/ s3://bucket-name

For example uploading the Hugo public directory to my website:
python s3cmd sync --acl-public --delete-removed --rr public/ s3://parsiya.net

  • --acl-public: Anyone can only read.
  • --delte-removed: Delete remove objects with no corresponding local files.

Changing the mime-type of css file after it is uploaded to avoid an old issue
python s3cmd --acl-public --no-preserve --mime-type="text/css" put public/css/hugo-octopress.css s3://parsiya.net/css/hugo-octopress.css

My runme.bat to upload my Hugo blog to the S3 bucket
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rd /q /s public
hugo
rd /q /s public\post
del /s /a .\*thumbs*.db
del /s /a public\categories\*index*.xml
del /s /a public\tags\*index*.xml
python s3cmd sync --acl-public --delete-removed -MP --rr public/ s3://parsiya.net
python s3cmd --acl-public --no-preserve --mime-type="text/css" put public/css/hugo-octopress.css s3://parsiya.net/css/hugo-octopress.css
rd /q /s public

Powershell

List all files (including hidden)
Get-ChildItem "searchterm" -recurse -force -path c:\ | select-object FullName

  • -recurse: recursive. Loops through all directories
  • -force: list hidden files.
  • select-object: Selects each file from last point
  • FullName: Only display file name

Diff in Powershell
Compare-Object (Get-Content new1.txt) (Get-Content new2.txt) | Format-List >> Diff-Output

Output will be in format of

  • InputObject: c:\users\cigital\somefile – line content
  • SideIndicator: => – exists in new2.txt (second file, file to the right)

Pseudo-grep in Powershell
findstr "something" *.txt

will include filename and line (no number AFAIK)

findstr /spin /c:"keyword" *.*
/s: recursive - will search through the current directory and all sub-directories
/p: skip binary files (or files with characters that cannot be printed)
/i: case-insensitive - remove if you want case sensitive search
/n: print line number

If you want to search for different keywords (with OR) remove the /c:

findstr /spin "keyword1 keyword2" *.*

will search for keyword1 OR keyword2 in files

https://technet.microsoft.com/en-us/library/Cc732459.aspx

grep in command outputs
whatever.exe | Select-String -pattern "admin"

Get-Acl amd icacls.exe
Get-Acl -path c:\windows\whatever.exe | Format-List

icacls.exe c:\windows\whatever.exe


Download Youtube videos with substitles

I love Wuxia (Chinese martial arts if I am not mistaken) series and movies. The following youtube-dl command will download the 56 episode HQ quality Chinese TV series called Xiao Ao Jiang Hu or Laughing in the Wind (also called The Smiling Proud Wanderer or Swordsman).

youtube-dl --ignore-errors --write-srt --sub-lang en --yes-playlist 'https://www.youtube.com/playlist?list=PLuGy72vdo4_ScwTYb1bAynhBs3KgowvvQ'

--ignore-errors: continue after errors (in the case of a playlist we do not want to be interrupted for one error)
--write-srt    : download substitles
--sub-lang     : subtitle language (in this case English)
--yes-playlist : link to a Youtube playlist

Youtube-dl can be downloaded using pip. For example on Windows:
python -m pip install youtube-dl.


Delete file or directory with a path or name over the Windows limit

Answer from superuser.com.

mkdir empty_dir
robocopy empty_dir the_dir_to_delete /s /mir
rmdir empty_dir
rmdir the_dir_to_delete

Some Git stuff because I keep forgetting them

Create new branch and merge
This works with small branches (e.g. one fix or so). Adapted from a Bitbucket tutorial.

  1. Create new branch - git branch fix-whatever
    This will create a branch of whatever branch you are currently on so make sure you are creating a branch from the branch you want.

  2. Switch to the branch - git checkout fix-whatever

  3. Make changes and commit - git add - git commit
    Make any changes you want to do, then stage and commit.

  4. Push the branch to remote repo [optional] - git push
    This can be safely done because it’s an obscure branch and no one else cares about it.

  5. Go back to the original branch to merge - git checkout master
    Master or whatever branch you were at step one.

  6. Merge the branches - git merge fix-whatever

  7. Delete branch - git branch -d fix-whatever
    We don’t need it anymore. If it was pushed to remote, then we need to delete it there too.

Only clone a certain branch
git clone -b <branch> <remote_repo>

Otherwise master will be cloned.

Undo remote git history after push
Because this keeps happening to me.

  1. Reset the head in local repo N commits back. - git reset HEAD~N
    Where N is the number of commits that you want to revert.

  2. Make changes and stage them - git add

  3. Commit the changes - git commit

  4. Force push the local repo to remote - git push -f
    Note this will force the update and erase the commit history online. If not one else is using the repo in between it’s ok.

Tags: tips and tricks

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