multi-line bash scripting

2020-03-19

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~2 min read

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244 words

In researching how to filter Git Commits by Author I found Adam Dymitruk’s bash solution.

git log --format='%H %an' |  # get a list of all commit hashes followed by the author name
  grep -v Adam |             # match the name but return the lines that *don't* contain the name
  cut -d ' ' -f1 |           # from this extract just the first part of the line which is commit ref
  xargs -n1 git log -1       # call git log from that commit stopped after 1 commit

The reason I’m writing about this is not the solution itself - which excludes any commits where the author name includes “Adam” - but because of the accompanying note:

Don’t be afraid to split your piped commands onto multiple lines. As long as a line ends with a pipe, bash knows there is more and will prompt for the next line. You can continue to do this until you have written what you want or pasted a multiline snippet from an example online. When you search history, it will be recalled as one line with proper semi-colons inserted if you used while loops or other flow control.

I was unaware of this feature but find its simplicity fantastic. Making use of multi-line bash commands can greatly improve the readability of a script - allowing both for improved documentation (as Adam did with comments) and smaller parts that a future reader must parse and understand.


Hi there and thanks for reading! My name's Stephen. I live in Chicago with my wife, Kate, and dog, Finn. Want more? See about and get in touch!