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docs: add example of bad code for documentation
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jamacku committed Aug 24, 2023
1 parent 96cbc0f commit a524a63
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37 changes: 31 additions & 6 deletions .github/workflows/differential-shellcheck.yml
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Expand Up @@ -10,7 +10,7 @@ permissions:
contents: read

jobs:
lint:
lint-latest:
name: Test latest changes
runs-on: ubuntu-latest

Expand All @@ -34,19 +34,44 @@ jobs:
run: |
sed -i "s/docker:\/\/ghcr\.io\/redhat-plumbers-in-action\/differential-shellcheck.*/Dockerfile/g" action.yml
- name: Differential ShellCheck - Full scan
continue-on-error: true
id: ShellCheck_Bad_Examples
uses: ./
with:
diff-scan: false
scan-directory: docs/**

- name: Differential ShellCheck - Diff scan
continue-on-error: true
uses: ./
with:
scan-directory: docs/**
token: ${{ secrets.GITHUB_TOKEN }}

- if: ${{ always() }}
name: Upload artifact with defects in SARIF format - Bad code examples
uses: actions/upload-artifact@0b7f8abb1508181956e8e162db84b466c27e18ce
with:
name: Differential ShellCheck SARIF of Bad code examples
path: ${{ steps.ShellCheck_Bad_Examples.outputs.sarif }}
retention-days: 7

- name: Differential ShellCheck - test current changes
id: ShellCheck
continue-on-error: true
id: ShellCheck_Latest
uses: ./
with:
exclude-path: |
test/**
src/**.{zsh,osh}
token: ${{ secrets.GITHUB_TOKEN }}
docs/**
token: ${{ secrets.GITHUB_TOKEN }}
- if: ${{ always() }}
name: Upload artifact with defects in SARIF format
name: Upload artifact with defects in SARIF format - Current changes
uses: actions/upload-artifact@0b7f8abb1508181956e8e162db84b466c27e18ce
with:
name: Differential ShellCheck SARIF
path: ${{ steps.ShellCheck.outputs.sarif }}
name: Differential ShellCheck SARIF of Current changes
path: ${{ steps.ShellCheck_Latest.outputs.sarif }}
retention-days: 7
120 changes: 120 additions & 0 deletions docs/example.sh
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#!/bin/sh
# Examples taken from the ShellCheck Gallery of bad code - https://github.com/koalaman/shellcheck#gallery-of-bad-code

# Quoting
# =======

echo $1 # Unquoted variables
rm "~/my file.txt" # Quoted tilde expansion
v='--verbose="true"'; cmd $v # Literal quotes in variables
touch $@ # Unquoted $@
echo 'Path is $PATH' # Variables in single quotes
trap "echo Took ${SECONDS}s" 0 # Prematurely expanded trap
unset var[i] # Array index treated as glob

# Conditionals
# ============

[[ n != 0 ]] # Constant test expressions
[[ -e *.mpg ]] # Existence checks of globs
[[ $foo==0 ]] # Always true due to missing spaces
[[ -n "$foo " ]] # Always true due to literals
[[ $foo =~ "fo+" ]] # Quoted regex in =~
[ foo =~ re ] # Unsupported [ ] operators
[ $1 -eq "shellcheck" ] # Numerical comparison of strings
[ $n && $m ] # && in [ .. ]
[[ "$$file" == *.jpg ]] # Comparisons that can't succeed
(( 1 -lt 2 )) # Using test operators in ((..))
[ x ] & [ y ] | [ z ] # Accidental backgrounding and piping

# Frequently misused commands
# ===========================

grep '*foo*' file # Globs in regex contexts
find . -exec foo {} && bar {} \; # Prematurely terminated find -exec
sudo echo 'Var=42' > /etc/profile # Redirecting sudo
time --format=%s sleep 10 # Passing time(1) flags to time builtin
alias archive='mv $1 /backup' # Defining aliases with arguments
tr -cd '[a-zA-Z0-9]' # [] around ranges in tr
exec foo; echo "Done!" # Misused 'exec'
find -name \*.bak -o -name \*~ -delete # Implicit precedence in find
find . -exec foo > bar \; # Redirections in find
f() { whoami; }; sudo f # External use of internal functions

# Common beginner's mistakes
var = 42 # Spaces around = in assignments
$foo=42 # $ in assignments
var$n="Hello" # Wrong indirect assignment
echo ${var$n} # Wrong indirect reference
var=(1, 2, 3) # Comma separated arrays
array=( [index] = value ) # Incorrect index initialization
echo $var[14] # Missing {} in array references
echo "Argument 10 is $10" # Positional parameter misreference
[ false ] # 'false' being true

# Style
# =====

[[ -z $(find /tmp | grep mpg) ]] # Use grep -q instead
a >> log; b >> log; c >> log # Use a redirection block instead
echo "The time is `date`" # Use $() instead
cd dir; process *; cd ..; # Use subshells instead
echo $[1+2] # Use standard $((..)) instead of old $[]
echo $(($RANDOM % 6)) # Don't use $ on variables in $((..))
echo "$(date)" # Useless use of echo
cat file | grep foo # Useless use of cat

# Data and typing errors
# ======================

args="$@" # Assigning arrays to strings
files=(foo bar); echo "$files" # Referencing arrays as strings
declare -A arr=(foo bar) # Associative arrays without index
printf "%s\n" "Arguments: $@." # Concatenating strings and arrays
[[ $# > 2 ]] # Comparing numbers as strings
var=World; echo "Hello " var # Unused lowercase variables
echo "Hello $name" # Unassigned lowercase variables
cmd | read bar; echo $bar # Assignments in subshells
cat foo | cp bar # Piping to commands that don't read
printf '%s: %s\n' foo # Mismatches in printf argument count
eval "${array[@]}" # Lost word boundaries in array eval

# Robustness
# ==========

rm -rf "$STEAMROOT/"* # Catastrophic rm
touch ./-l; ls * # Globs that could become options
find . -exec sh -c 'a && b {}' \; # Find -exec shell injection
printf "Hello $name" # Variables in printf format
export MYVAR=$(cmd) # Masked exit codes

# Portability
# ===========

echo {1..$n} # Works in ksh, but not bash/dash/sh
echo {1..10} # Works in ksh and bash, but not dash/sh
echo -n 42 # Works in ksh, bash and dash, undefined in sh
expr match str regex # Unportable alias for `expr str : regex`
trap 'exit 42' sigint # Unportable signal spec
cmd &> file # Unportable redirection operator
read foo < /dev/tcp/host/22 # Unportable intercepted files
foo-bar() { ..; } # Undefined/unsupported function name
[ $UID = 0 ] # Variable undefined in dash/sh
local var=value # local is undefined in sh
time sleep 1 | sleep 5 # Undefined uses of 'time'

# Miscellaneous
# =============

PS1='\e[0;32m\$\e[0m ' # PS1 colors not in \[..\]
PATH="$PATH:~/bin" # Literal tilde in $PATH
rm “file” # Unicode quotes
echo "Hello world" # Carriage return / DOS line endings
echo hello \ # Trailing spaces after \
var=42 echo $var # Expansion of inlined environment
echo $((n/180*100)) # Unnecessary loss of precision
ls *[:digit:].txt # Bad character class globs
sed 's/foo/bar/' file > file # Redirecting to input
var2=$var2 # Variable assigned to itself
[ x$var = xval ] # Antiquated x-comparisons
ls() { ls -l "$@"; } # Infinitely recursive wrapper

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