Small examples of bash scripting.
| Element | Notation | Example | Notes |
|---|---|---|---|
| Constants | SCREAMING_SNAKE_CASE | DEST_PATH | Use readonly or declare -r to ensure they are readonly. |
| Environment variable names | SCREAMING_SNAKE_CASE | PATH | |
| File | snake_case | my_script | Executables should not have extension (strongly preferred) or a .sh extension.1 |
| Functions | snake_case | do_something(){ } | The keyword function it's optional, but must be used consistently troughout a project.2 |
| Hashbang | #!/usr/bin/env bash | #!/usr/bin/bash asumes it's always installed in /bin, which can cause issues.3 | |
| Local variables | snake_case | my_local_variable | Ensure that local variables are only seen inside a function and it's children by using local when declaring them. |
| Variables | snake_case | user_name |
: '
line1
line2
'bash -x ./script#/usr/bin/env bash -xset -x
echo "Code block"
set +xAlways check return values and give informative return values.
For unpiped commands use $? or check directly via an if statement.
if ! mv "${file_list[@]}" "${dest_dir}/"; then
echo "Unable to move ${file_list[*]} to ${dest_dir}" >&2
exit 1
fi
# Or
mv "${file_list[@]}" "${dest_dir}/"
if (( $? != 0 )); then
echo "Unable to move ${file_list[*]} to ${dest_dir}" >&2
exit 1
fiGiven the choice between invoking a shell builtin and invoking a separete process, choose the builtin.
# Prefer this:
addition=$(( X + Y ))
substitution="${string/#foo/bar}"
# Instead of this:
addition="$(expr "${X}" + "${Y}")"
substitution="$(echo "${string}" | sed -e 's/^foo/bar/')"Use ShellCheck to get warnings and suggestions for your scripts.
If you find these examples useful, you can star this repo.
React
Typescript
Django
Laravel
Facebook
Microsoft
Google
Alibaba
D3
Tencent