Helper methods for prettier shell scripting
Note: The shell script is on the gh-pages branch, for the sake of the shorter URL.
Include this line at the top of your shell script:
eval "$(cat ~/.local/share/shelper.sh || curl suderman.github.io/shelper/shelper.sh)"
###has
Pass this a command as an argument to find out if it exists. For example:
if has tmuxifier; then
eval "$(tmuxifier init -)"
fi
(has brew) && brew_prefix="$(brew --prefix)"
This also works with files and directories. For example:
(has ~/.vimrc) || echo "Don't you like Vim?"
###hasnt
Exactly the same as the previous method, but the other way around.
###defined
Pass this a variable to find out if it exists (non-empty). For example:
defined $HERO || HERO="Speed Racer"
###undefined
Exactly the same as the previous method, but the other way around.
###msg
Pass this a message you want printed out all pretty-like. For example:
msg "Updating the system..."
###ask
Pass this a message and it will return true if the user presses y. For
example:
if ask "Are you sure?"; then
echo "Okay, great!"
fi
###source
Pass this a local file to try to source (this is normal behaviour). For example:
source ~/.local/zsh/script.sh
Pass this a URL to a remote script, saving it to the cache for later use. For example:
source www.example.com/script.sh
Pass this a local file to try to source, and an URL to fall back on if it doesn't exist. For example:
source ~/.local/zsh/script.sh www.example.com/script.sh
###source if
Source a script, but only if it exists on the local file system. For example:
source if ~/.local/zsh/script.sh
###source new
Source a remote script, skipping the cache and fetching it new. For example:
source new www.example.com/script.sh
###is
Check type of shell and OS. For example:
(is bash) && echo "This shell is Bash"
(is zsh) && echo "This shell is ZSH"
(is osx) && echo "This OS is OS X"
(is ubuntu) && echo "This OS is Ubuntu"
###copy
Give this a source file and a destination file to copy to. This is normal behaviour for cp, except the destination will always be overwritten and directories will always copy recursvively (cp -rf). When overwriting, a backup copy of the destination is created (.bak) in the destination's directory. Also, the destination's directory structure will be built if neccessary with mkdir -p.
For example:
copy ~/downloads/file.txt ~/unmade/nested/directories/myfile.txt
Alternatively pass a URL as the source to download the remote file to the local destination. For example:
copy www.example.com/file.txt ~/unmade/nested/directories/myfile.txt
###append
Append a line to the end of file (only if it doesn't already exist). For example:
append "this new line will only appear once" ~/mylog.txt
###ref
Save an environment variable to disk, or load it from disk if it doesn't exist. For example:
MY_VARIABLE=$(ref MY_VARIABLE)'
In the above example, assume MY_VARIABLE was previously assigned a value of 42. After running this command, MY_VARIABLE continues to equal 42, but now this value is also saved to disk. If this same command was run in a later session where MY_VARIABLE had no value, its value of 42 would be restored from disk.
Additionally, a default value can be passed for situations where the initial value is empty. For example:
MY_VARIABLE=$(ref MY_VARIABLE 'my default value')'
###deref
Dereference (expand) $VARIABLES in a file and replace with the literal values to disk. For example:
deref ~/file-to-be-replaced-with-dereferenced-contents.txt
###keyval
Look up key-value pair from CSV string, searching by key or position (:first, :last, :1, :2, etc). For example:
keyval larry "bob:s3cret,larry:passw0rd,admin:priv4te"
keyval :first "bob:s3cret,larry:passw0rd,admin:priv4te"
keyval :all "bob:s3cret,larry:passw0rd,admin:priv4te"
###key
Look up key from CSV string, searching by value or position (:first, :last, :1, :2, etc).
###val
Look up value from CSV string, searching by key or position (:first, :last, :1, :2, etc).
###trim
Trim surrounding whitespace from a string. For example:
trim " mystring "
###waitfor
Make a script wait for a host to be ready. This can potentially block a script indefinitely. The first argument is host:port and the default check is curl. For example:
waitfor 10.0.0.5:8080
If the port is 3306, it will try to log into MySQL instead. The second argument is the path to the certificate and key (file extensions .crt and .key will be appended). For example:
waitfor 10.0.0.5:3306 ~/certs/myserver
###shelper
Call this to delete the local copy, download it fresh, and then reload this script.