Merge pull request #92 from terminalforlife/master

New Examples & `sysctl` File + Wording & Formatting Improvements

sheets/git

@@ -1,46 +1,45 @@
-# To set your identity:
+# Set your identity.
 git config --global user.name "John Doe"
 git config --global user.email johndoe@example.com
 
-# To set your editor:
+# Set your editor.
 git config --global core.editor emacs
 
-# To enable color:
+# Enable color support for commands like `git diff`. Disable with `never` or
+# partially disable -- unless otherwise applied -- with `false`.
 git config --global color.ui true
 
-# To stage all changes for commit:
-git add --all
+# Stage all changes for commit.
+git add [--all|-A]
 
-# To stash changes locally, this will keep the changes in a separate changelist
-# called stash and the working directory is cleaned. You can apply changes
-# from the stash anytime
+# Stash changes locally. This will keep the changes in a separate changelist, -
+# called 'stash', and the working directory is cleaned. You can apply changes
+# from the stash at any time.
 git stash
 
-# To stash changes with a message
+# Stash changes with a message.
 git stash save "message"
 
-# To list all the stashed changes
+# List all the stashed changes.
 git stash list
 
-# To apply the most recent change and remove the stash from the stash list
+# Apply the most recent change and remove the stash from the stash list.
 git stash pop
 
-# To apply any stash from the list of stashes. This does not remove the stash
-# from the stash list
+# Apply stash from the stash list, but does not remove the stash from the list.
 git stash apply stash@{6}
 
-# To commit staged changes
+# Commit staged changes.
 git commit -m "Your commit message"
 
-# To edit previous commit message
+# Edit previous commit message.
 git commit --amend
 
-# Git commit in the past
+# Commit in the past. Newer versions of Git allow `--date="2 days ago"` usage.
 git commit --date="`date --date='2 day ago'`"
 git commit --date="Jun 13 18:30:25 IST 2015"
-# more recent versions of Git also support --date="2 days ago" directly
 
-# To change the date of an existing commit
+# Change the date of an existing commit.
 git filter-branch --env-filter \
     'if [ $GIT_COMMIT = 119f9ecf58069b265ab22f1f97d2b648faf932e0 ]
      then
@@ -48,144 +47,142 @@ git filter-branch --env-filter \
          export GIT_COMMITTER_DATE="Sat May 19 01:01:01 2007 -0700"
      fi'
 
-# To removed staged and working directory changes
+# Remove staged and working directory changes.
 git reset --hard
 
-# To go 2 commits back
+# Go 2 commits back.
 git reset --hard HEAD~2
 
-# To remove untracked files
+# Remove untracked files.
 git clean -f -d
 
-# To remove untracked and ignored files
+# Remove untracked and ignored files.
 git clean -f -d -x
 
-# To push to the tracked master branch:
+# Push to the tracked master branch.
 git push origin master
 
-# To push to a specified repository:
-git push git@github.com:username/project.git
+# Push to a specified repository.
+git push git@github.com:[USER_NAME]/[REPO_NAME].git
 
-# To delete the branch "branch_name"
-git branch -D branch_name
+# Delete the branch "branch_name".
+git branch -D [BRANCH]
 
-# To make an existing branch track a remote branch
+# Make an existing branch track a remote branch.
 git branch -u upstream/foo
 
-# To list all local and remote branches
+# List all local and remote branches.
 git branch -a
 
-# To see who committed which line in a file
-git blame filename
-
-# To sync a fork with the master repo:
-git remote add upstream git@github.com:name/repo.git    # Set a new repo
-git remote -v                                           # Confirm new remote repo
-git fetch upstream                                      # Get branches
-git branch -va                                          # List local - remote branches
-git checkout master                                     # Checkout local master branch
-git checkout -b new_branch                              # Create and checkout a new branch
-git merge upstream/master                               # Merge remote into local repo
-git show 83fb499                                        # Show what a commit did.
-git show 83fb499:path/fo/file.ext                       # Shows the file as it appeared at 83fb499.
-git diff branch_1 branch_2                              # Check difference between branches
-git log                                                 # Show all the commits
-git status                                              # Show the changes from last commit
-
-# Commit history of a set of files
+# See who committed which line in a file.
+git blame [FILE]
+
+# Sync a fork with the master repo.
+git remote add upstream git@github.com:name/repo.git # <-- Set a new repo.
+git remote -v # <-- Confirm new remote repo.
+git fetch upstream # <-- Get branches.
+git branch -va # <-- List local - remote branches.
+git checkout master # <-- Checkout local master branch.
+git checkout -b new_branch # <-- Create and checkout a new branch.
+git merge upstream/master # <-- Merge remote into local repo.
+git show 83fb499 # <-- Show what a commit did.
+git show 83fb499:path/fo/file.ext # <-- Show the file as it was in 83fb499.
+git diff branch_1 branch_2 # <-- Check difference between branches.
+git log # <-- Show all of the commits.
+git status # <-- Show the changes from the last commit.
+
+# Display the commit history of a set of files.
 git log --pretty=email --patch-with-stat --reverse --full-index -- Admin\*.py > Sripts.patch
 
-# Import commits from another repo
+# Import commits from another repo.
 git --git-dir=../some_other_repo/.git format-patch -k -1 --stdout <commit SHA> | git am -3 -k
 
-# View commits that will be pushed
+# View commits which would be pushed.
 git log @{u}..
 
-# View changes that are new on a feature branch
+# View changes which are new on a feature branch.
 git log -p feature --not master
 git diff master...feature
 
-# Interactive rebase for the last 7 commits
+# Interactive rebase for the last 7 commits.
 git rebase -i @~7
 
-# Diff files WITHOUT considering them a part of git
-# This can be used to diff files that are not in a git repo!
+# Show changes to files WITHOUT considering them a part of git. This can be
+# used to diff files which are not part of a git repo!
 git diff --no-index path/to/file/A path/to/file/B
 
-# To pull changes while overwriting any local commits
+# Pull changes, while overwriting any local commits.
 git fetch --all
 git reset --hard origin/master
 
-# Update all your submodules
+# Update all submodules.
 git submodule update --init --recursive
 
-# Perform a shallow clone to only get latest commits
-# (helps save data when cloning large repos)
+# Perform a shallow clone, to only get the latest commits, which helps to save
+# data (good for limited data connections) when cloning large repos.
 git clone --depth 1 <remote-url>
 
-# To unshallow a clone
+# Unshallow a clone.
 git pull --unshallow
 
-# Create a bare branch (one that has no commits on it)
+# Create a bare branch; without any commits.
 git checkout --orphan branch_name
 
-# Checkout a new branch from a different starting point
+# Checkout a new branch from a different starting point.
 git checkout -b master upstream/master
 
-# Reset local branch to upstream branch and then checkout it
+# Reset local branch to upstream branch, then checkout it.
 git checkout -B master upstream/master
 
-# Remove all stale branches (ones that have been deleted on remote)
-# So if you have a lot of useless branches, delete them on Github and then run this
+# Remove all stale branches; ones that have been deleted on remote. So if you
+# have a lot of useless branches, delete them on GitHub and then run this.
 git remote prune origin
 
-# The following can be used to prune all remotes at once
+# Prune all remotes at once.
 git remote prune $(git remote | tr '\n' ' ')
 
-# Revisions can also be identified with :/text
-# So, this will show the first commit that has "cool" in their message body
+# Revisions can also be identified with `:/text`. So, this will show the first
+# commit that has the string "cool" in its message body.
 git show :/cool
 
-# Undo parts of last commit in a specific file
+# Undo parts of the last commit in a specific file.
 git checkout -p HEAD^ -- /path/to/file
 
-# Revert a commit and keep the history of the reverted change as a separate revert commit
+# Revert a commit, but keep the history of the event as a separate commit.
 git revert <commit SHA>
 
-# Pick a commit from a branch to current branch. This is different than merge as
-# this just applies a single commit from a branch to current branch
-git cherry-pick <commit SHA1>
+# Apply only the changes made within a given commit. This is different to the
+# `merge` command, as it would otherwise apply all commits from a branch.
+git cherry-pick [HASH]
 
-# Undo last commit
-# If you want to nuke commit C and never see it again
+# Undo last commit. If you want to nuke commit C to never see it again:
 #    (F)
 # A-B-C
 #     ↑
 #   master
 git reset --hard HEAD~1
 
-# Undo last commit
-# If you want to undo the commit but keep your changes
+# Undo last commit. If you want to undo the commit, but keep your changes:
 #    (F)
 # A-B-C
 #   ↑
 # master
 git reset HEAD~1
 
-# list files changed in ${commit_id}
-git diff-tree --no-commit-id --name-only -r ${commit_id}
+# List files changed in a given commit.
+git diff-tree --no-commit-id --name-only -r [HASH]
 
-# list files changed in ${commit_id}, porcelain way, meant to be user facing
+# Porcelain-ly List files changed in a given commit; user-facing approach.
 git show --pretty="" --name-only bd61ad98
 
-# See everything you have done, across branches, in a glance,
-# then go to the place right before you broke everything
+# See everything you have done, across branches, in a glance, then go to the
+# place right before you broke everything.
 git reflog
 git reset HEAD@{hash}
 
-# To move your most recent commit from one branch and stage it on TARGET branch
+# Move your most recent commit from one branch, to stage it on [BRANCH].
 git reset HEAD~ --soft
 git stash
-git checkout TARGET
+git checkout [BRANCH]
 git stash pop
 git add .

sheets/perl

@@ -28,3 +28,6 @@ perl -p -i'.old' -e 's/find/replace/g' filename
 #   learn perl:         /perl/:learn
 #   perl one-liners:    /perl/1line
 #   search in pages:    /perl/~keyword
+
+# Perl method of listing out the environment variables, sans values.
+perl -e 'print("$_\n") foreach keys(%ENV)'

sheets/ssh

@@ -1,58 +1,60 @@
 # ssh
 # access a remote host via SSH
 
-# To ssh via pem file (which normally needs 0600 permissions):
+# SSH in via PEM file, which normally needs 0600 permissions.
 ssh -i /path/to/file.pem user@example.com
 
-# To connect on an non-standard port:
+# Connect through a non-standard port. It's recommended not to use the default
+# port of 22, as it is so often targeted, due to it being so commonplace.
 ssh -p 2222 user@example.com
 
-# To connect and forward the authentication agent
+# Connect and forward the authentication agent.
 ssh -A user@example.com
 
-# To execute a command on a remote server:
+# Execute a command on a remote server.
 ssh -t user@example.com 'the-remote-command'
 
-# To tunnel an x session over SSH:
+# Tunnel an X session over SSH, via X11 Forwarding.
 ssh -X user@example.com
 
 # Redirect traffic with a tunnel between local host (port 8080) and a remote
-# host (remote.example.com:5000) through a proxy (personal.server.com):
+# host (remote.example.com:5000) through a proxy (personal.server.com).
 ssh -f -L 8080:remote.example.com:5000 user@personal.server.com -N
 
-# To launch a specific x application over SSH:
+# Launch a specific X application over SSH.
 ssh -X -t user@example.com 'chromium-browser'
 
-# To create a SOCKS proxy on localhost and port 9999
+# Create a SOCKS proxy on localhost and port 9999.
 ssh -D 9999 user@example.com
 
-# -X use an xsession, -C compress data, "-c blowfish" use the encryption blowfish
-ssh user@example.com -C -c blowfish -X
+# Connect to server, but allow for X11 forwarding, while also using GZip
+# compression (can be much faster; YMMV), and using the `blowfish` encryption.
+# For more information, see: http://unix.stackexchange.com/q/12755/44856
+ssh -XCc blowfish user@example.com
 
-# For more information, see:
-# http://unix.stackexchange.com/q/12755/44856
+# Copy files and directories, via SSH, from remote host to the current working
+# directory, with GZip compression. An option for when `rsync` isn't available.
+#
+# This works by creating (not temporary!) a remote Tar archive, then piping its
+# output to a local Tar process, which then extracts it to STDOUT.
+ssh user@example.com 'tar -C /var/www/Shared/ zcf - asset1 asset2' | tar zxf -
 
-# Copy files and folders through ssh from remote host to pwd with tar.gz compression
-# when there is no rsync command available
-ssh user@example.com "cd /var/www/Shared/; tar zcf - asset1 asset2" | tar zxf -
-
-# explicitly specify a key for connection
-# (if you have Too many authentication failures for *username*)
+# Explicitly specify a key for connection. Useful if you have too many
+# authentication failures for a given username.
 ssh -i some_id_rsa -o IdentitiesOnly=yes them@there:/path/
 
-# switch off pubkey authentication
+# Temporarily disable `pubkey` authentication for this instance.
 ssh -o PubkeyAuthentication=no username@hostname.com
 
-# Mount folder/filesystem through SSH
-# Install SSHFS from https://github.com/libfuse/sshfs
-# Will allow you to mount a folder securely over a network.
+# Mount a remote directory or filesystem, through SSH, to a local mountpoint.
+# Install SSHFS from: https://github.com/libfuse/sshfs
 sshfs name@server:/path/to/folder /path/to/mount/point
 
-# Emacs can read file through SSH
+# EMACS can read files through SSH.
 # Doc: http://www.gnu.org/software/emacs/manual/html_node/emacs/Remote-Files.html
 emacs /ssh:name@server:/path/to/file
 
-# Get help on SSH escape sequences
-# Useful for terminating unresponsive sessions
-# The default escape character is ~ (tilde), escapes are only recognized immediately after newline
-$ [Enter]~?
+# Get help for SSH escape sequences. Useful for terminating unresponsive
+# sessions. The default escape character is ~ (tilde), escapes are only
+# recognized immediately after a newline.
+$ <Enter>~?

sheets/sysctl

@@ -0,0 +1,12 @@
+# List all kernel keys (parameters) and their values.
+sysctl [--all|-a]
+# As above, but show only specified keys and their values.
+sysctl [KEY_1 [KEY_2] ...]
+
+# As above, but instead output only the values.
+sysctl [--values|-n] [KEY_1 [KEY_2] ...]
+# Not nearly as useful, but alternatively, output only the key names.
+sysctl [--names|-N] [KEY_1 [KEY_2] ...]
+
+# Assign one or more kernel keys a new value; usually requires root access.
+sysctl [KEY_1=VALUE_1 [KEY_2=VALUE_2] ...]

sheets/tee

@@ -1,16 +1,15 @@
-# To tee stdout to a file:
+# Display `ls` output to the user, but also write it to the given file.
 ls | tee outfile.txt
-
-# To tee stdout and append to a file:
+# As above, but amend the data; previous file's data remains in-tact.
 ls | tee -a outfile.txt
 
-# tee would take the output of the first command in the pipeline and copy it 
-# to standard output (the terminal) while also making copies of it in the files one, two and three:
-somecommand | tee one two three
+# Pipe the standard output of a given command into `tee`, which then displays
+# it to the user and sending the data to files `one`, `two`, and `three`.
+[COMMAND] | tee one two three
 
-# write 3 to /proc/sys/vm/drop_caches (with root rights)
+# Workaround to output data to a file, with root privileges.
 echo 3 | sudo tee /proc/sys/vm/drop_caches
 
-# in Vim:
-# The structure :w !cmd means "write the current buffer piped through command".
+# Pipe the current Vim buffer to a shell process, which in this case is `tee`.
+# This is especially useful as a shortcut added to `.vimrc` or similar.
 :w !sudo tee %