Pragmatism in the real world
Recently, I was writing a bash script that read a file into a string and then passed that string elsewhere that then calculated the hash of it. To my surprise, I was getting a different hash to doing the equivalent in PHP with file_get_contents(). Digging into it, I discovered that when you assign the output of cat to a variable, the trailing new line in the file is stripped off, which explained the difference. You… continue reading.
If you want to see the hex values of a file, the easiest way to do this is to use xxd. Given foo.txt that contains "This is some text!": $ xxd foo.txt 00000000: 5468 6973 2069 7320 736f 6d65 2074 6578 This is some tex 00000010: 7421 0a t!. There are three columns in the output: number of first character in hex Hex representation of up to 16 bytes, separated every 2 bytes ASCII representation,… continue reading.
When printing output in a shell script, it's quite useful to be able to indent information to group it. The easiest way to do this is with pr, like this: body=$(curl -s "http://localhost:8888/") echo "Response:" echo "$body" | pr -to 4 This generates: Response: { "links": { "games": "/games" } } Given that pr appeared in version 1 of AT&T Unix, I'm late to the party with this one, but it's a useful thing to… continue reading.
When writing a shell script recently, I realised that it would be really handy to get the the status code from a curl command in addition to the body. Usually, I call curl like this: body=$(curl -s "http://localhost:8888/") echo "Curl exit code: $?" echo "Body: $body" This works well, but no status code is available as curl's exit code is related to its own error system, not the HTTP call. Searching Stack Overflow, I came… continue reading.
My accountant recently moved my business accounts system over to FreeAgent. One thing I like to do is keep a copy of every invoice PDF that I issue in a folder on my computer as a back up, just in case the online systems let me down. As I was learning new systems, I took advantage of this time to write a script to rename the invoice PDFs from Nineteen-Feet-Limited_Invoice_123.pdf to my preferred format of… continue reading.
One thing that I like to do is write a script for seemingly trivial things that I do more than once. I do this as it turns out that I end up needing them again. One example is a pair of script I use when testing rst2pdf. rst2pdf's tests work by creating a PDF and then comparing this to a reference PDF. If they are different, then the test has failed. When a test fails,… continue reading.
I have a set of Markdown files with YAML front matter that contains a created property containing the date that the file was created. Due to various machinations, the file creation date no longer matches this date, so I thought I'd fix this. Setting created date of a file On macOS, to change a file's creation date you use SetFile which is installed as part of Xcode. Irritatingly, it uses US format dates: SetFile -d… continue reading.
