Bash style

Bash is frequently used in our build, CI and deployment systems. Some general guidelines and recommended reading

• Bash style
  • Reading from a file
  • Set -eu -o pipefail
  • References

Reading from a file

Prefer using mapfile instead of while IFS to read a file

mapfile -t myArray < file.txt

mapfile -t myArray < <(find -d .)

instead of

input="/path/to/txt/file"
while IFS= read -r line
do
  echo "$line"
done < "$input"

Set -eu -o pipefail

This is generally "bash strict mode" and sets

• e exit if error
• u error on variable unset (and exit)
• -o pipefail fail if items in the pipe | fail. Bash otherwise continues if error | pass which causes some unexpected behavior.

Recommend using these at the start of all scripts and specifically disabling if a section of a bash script does not need them (for example, you want to let a pipe fail).

Utilities in use

We use shfmt and shellcheck for our shell script linters

References

https://wiki.bash-hackers.org/ https://www.notion.so/daxmc99/One-liners-Basic-Cheat-sheet-Linux-Command-Library-b3676fb5a49b44f8a507cce0185ca5d7