Notes on Web and Mobile App Development

Even if a company unifies the technology for integration, they run into problems with differences in business process and conceptual dissonance with the data. One division of the company may think a customer is someone with whom it has a current agreement; another division also counts those that had a contract but don’t any longer; another counts product sales but not service sales. That may sound easy to sort out, but when you have hundreds of records in which every field can have a subtly different meaning, the sheer size of the problem becomes a challenge—even if the only person who knows what the field really means is still with the company. (And, of course, all of this changes without warning.) As a result, data has to be constantly read, munged, and written in all sorts of different syntactic and semantic formats. Then there’s the matter of what comes under the term “business logic.” I find this a curious term because there are few things that are less logical than business logic...

https://stackoverflow.com/questions/1401482/yyyy-mm-dd-format-date-in-shell-script In bash (>=4.2) it is preferable to use printf's built-in date formatter (part of bash) rather than the external date (usually GNU date). As such: # put current date as yyyy-mm-dd in $date # -1 -> explicit current date, bash >=4.3 defaults to current time if not provided # -2 -> start time for shell printf -v date '%(%Y-%m-%d)T\n' -1  # put current date as yyyy-mm-dd HH:MM:SS in $date printf -v date '%(%Y-%m-%d %H:%M:%S)T\n' -1  # to print directly remove -v flag, as such: printf '%(%Y-%m-%d)T\n' -1 # -> current date printed to terminal In bash (<4.2): # put current date as yyyy-mm-dd in $date date=$(date '+%Y-%m-%d') # put current date as yyyy-mm-dd HH:MM:SS in $date date=$(date '+%Y-%m-%d %H:%M:%S') # print current date directly echo $(date '+%Y-%m-%d') Other available date formats can be viewed from the date man pages (for external ...

https://stackoverflow.com/questions/23489934/echo-2-some-text-what-does-it-mean-in-shell-scripting To quickly explain what the others missed: echo "hey" >&2 > redirect standard output (implicit 1> ) & what comes next is a file descriptor, not a file (only for right hand side of >) 2 stderr file descriptor number Redirect stdout from echo command to stderr. (If you were to useecho "hey" >2 you would output hey to a file called 2) https://stackoverflow.com/questions/41127585/shell-how-to-check-available-space-and-exit-if-not-enough #!/bin/bash # Note: Numbers are 1024-byte units on Linux, #       and 512-byte units on macOS. reqSpace=100000000 availSpace=$(df "$HOME" | awk 'NR==2 { print $4 }') if (( availSpace < reqSpace )); then   echo "not enough Space" >&2   exit 1 fi

https://docs.aws.amazon.com/cli/latest/userguide/cli-services-glacier.html => Using aws glacier CLI (vs aws s3). This is different with aws s3 with --storage-class GLACIER. See  https://www.reddit.com/r/aws/comments/7y9z7f/whats_the_difference_between_s3_glacier_storage/ What's the difference between S3 Glacier storage class, and the Glacier vaults? I'm confused about the difference between: storing data in an S3 bucket, marked as storage class "GLACIER" creating a Glacier vault in the AWS console and using that instead https://stackoverflow.com/questions/62121247/aws-s3-glacier-upload-archive-taking-a-long-time-to-finish-execution-ways-to-c https://ystatit.medium.com/what-is-aws-s3-glacierstagingstorage-cost-a0c0be216589 https://stackoverflow.com/questions/44912550/multipart-upload-to-amazon-glacier-content-range-incompatible-with-content-leng https://stackoverflow.com/questions/46111372/change-s3-bucket-storage-class-to-s3-infrequent-access https://docs.aws.amazo...

https://www.linux.com/training-tutorials/linux-shell-tip-remove-files-names-contains-spaces-and-special-characters-such/

 https://unix.stackexchange.com/questions/137037/restrict-user-access-in-linux https://superuser.com/questions/581194/setting-correct-permissions-for-uploading-files https://en.wikipedia.org/wiki/Restricted_shell https://unix.stackexchange.com/questions/208960/how-to-restrict-a-user-to-one-folder-and-not-allow-them-to-move-out-his-folder https://ostechnix.com/the-right-way-to-edit-etc-passwd-and-etc-group-files-in-linux/

How Do I Know That I’m Not Breaking Anything?  Code is a strange sort of building material. Most materials that you can make things from, such as metal, wood, and plastic, fatigue. They break when you use them over time. Code is different. If you leave it alone, it never breaks. Short of the stray cosmic ray flipping a bit on your storage media, the only way it gets a fault is for someone to edit it. Run a machine made of metal over and over again, and it will eventually break. Run the same code over and over again, and, well, it will just run over and over again. The  Software Crafters community The  Legacy Code Rocks community The  WeDoTDD community