Reference Pages

Misc

Data Stuff

HL7 Mirth Connect

Escape Sequences

Sequence Replacement  
\F\ | Field Separator (MSH-1)
\S\ ^ Subfield Separator MSH-2
\R\ ~ Repetition Separator MSH-2
\E\ \ Escape Character MSH-2
\T\ & Subcomponent Separator MSH-2
\.br\ \n Carriage Return (nonstandard?)
\X0D\ \n Carriage Return (Using \x##\ + Hex Character #)
\X0A\ \r Line Feed (Using \x##\ + Hex Character #)

Java

Tools

JavaScript

Fundamental Objects

Linux

Output, Summarize, or Hash Files  
Write and concatenate files cat
Transform data into printable data base64
Output the first part of a file head
Output the last part of a file tail
Split a file into pieces split
Print newline, word, and byte counts wc
Print or check MD5 digests md5sum
Print or check SHA-1 digests sha1sum
Operating on File Contents/Sorting  
Sort text files sort
Shuffle text files shuf
Uniquify files uniq
Compare two sorted files by line comm
Join lines on a common field join
Print a line of text echo
Directory Listing and Operations  
List directory contents ls
Color setup for ls dircolors
Copy files and directories cp
Copy files and set attributes install
Convert and copy a file dd
Move or rename files or directories mv
Remove (delete) files or directories rm
Remove files more securely shred
Make links between files ln
Make a new directory mkdir
Print the value of a symlink or cannonical file name readlink
Remove an empty directory rmdir
Remove files via the unlink syscall unlink
Report file system space usage df
Estimate file space usage du
Report file or file system status stat
File Attribute Manipulation  
Change file owner and group chown
Change file group ownership chgrp
Change file access permissions chmod
Change file timestamp touch
File Name Manipulation  
Strip directory and suffix from a file name basename
Strip last file name component dirname
Check file name validity and portability pathchk
Print the resolved file name realpath
Working Context  
Print the current working directory pwd
Print all or some environment variables printenv
Run a command immune to hangups nohup
Send a signal to a process kill

Regular Expressions

Metacharacters that must be escaped: ^ [ . $ { * ( ) \ + | ? < >

Anchors  
^ start of line
$ end of line
\A start of string
\Z end of string
\b word boundary
\B not word boundary
\< start of word ⚠️
\> end of word ⚠️
Quantifiers  
* 0 or more
*? 0 or more, ungreedy
+ 1 or more
+? 1 or more, ungreedy
? 0 or 1
?? 0 or 1, ungreedy
{#} Exacty # (e.g., {3} = exactly 3)
{#,} # or more (e.g., {3,} = 3 or more)
{#,}? # or more, ungreedy
{#,#} # to # matches, inclusive (e.g., {3,5} = 3, 4, or 5)
{#,#}? # to # matches, inclusive and ungreedy
Ranges  
. any character, typically excluding newline/linefeed
| or (e.g., a | b matches a or b)
() capturing group (e.g., Date: (\d{4}-\d{2}-\d{2}))
(?:) non-capturing/passive group (e.g., (?:this|that))
[] characer range
[^] negative characer range
Character Class  
\c control character (e.g., ASCII 0-31 & 127), same as POSIX [:word:]
\s white space (e.g., [\t\n\f\r ] tab, newline, form feed, carriage returm, space)
\S not white space
\d digit (e.g., [0-9])
\D not digit
\w word (e.g., [A-Za-z0-9_])
\W not word
Escape Sequences  
\\ literal backslash `
\t tab
\n newline/linefeed
\r carriage return
\f form feed
\a alarm/bell
\xhh hexadecimal character hh
\xxx \oxxx \Oxxx octal character xxx
\Q quote (disable pattern metacharacters)
\E end quote (re-enable pattern metacharacters)
POSIX Character Class  
[:upper:] any uppercase character (e.g., [A-Z])
[:lower:] any lowercase character (e.g., [a-z])
[:alpha:] any alphabetical character (e.g., [A-Za-z])
[:alnum:] any alphanumeric character (e.g., [A-Za-z0-9])
[:digit:] any decimal digit (e.g., [0-9])
[:xdigit:] any hexadecimal digit (e.g., [0-9a-fA-F])
[:punct:] any graphical character excluding “word” chartacters (e.g., [-!"#$%&'()*+,./:;<=>?@[\\\]^_`{\|}~])
[:blank:] any horizontal whitespace character (e.g., space or tab \t)
[:space:] any whitespace character, similar to \s\ but also includes vertical tab \X0B / \013
[:cntrl:] any control character (ASCII 0-31 & 127), same as \c
[:graph:] any character that is graphical, that is, visible. This class consists of all alphanumeric characters and all punctuation characters
[:print:] all printable characters, which is the set of all graphical characters plus those whitespace characters which are not also controls.
[:word:] any “word” character (e.g., [A-Za-z0-9_]), same as \w
Backreferences ⚠️  
$n or \n nth capturing group
$` before matched string
$' after matched string
$+ last matched string
$& entire matched string
$_ entire input string
$$ literal dollar sign $

⚠️ Not universally supported

SSL Certificates

Using Certbot with unexposed domains

cloudflare.ini:

# Cloudflare API token used by Certbot
dns_cloudflare_api_token = be967a3beb4d7048d57f1b3ddc51d52d

commands:

apt install certbot python-is-python3 python3-certbot-dns-cloudflare
certbot certonly --dns-cloudflare --dns-cloudflare-credentials /path/to/cloudflare.ini -d domain.name.com -n

Time Zones

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