Showing 115 of 117 total issues
Literal """Method called for every year"""
used in void context. Open
"""Method called for every year"""
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This cop checks for operators, variables and literals used in void context.
Example:
# bad
def some_method
some_num * 10
do_something
end
Example:
# bad
def some_method(some_var)
some_var
do_something
end
Example:
# good
def some_method
do_something
some_num * 10
end
Example:
# good
def some_method(some_var)
do_something
some_var
end
Literal """Returns a hash of shows by year"""
used in void context. Open
"""Returns a hash of shows by year"""
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This cop checks for operators, variables and literals used in void context.
Example:
# bad
def some_method
some_num * 10
do_something
end
Example:
# bad
def some_method(some_var)
some_var
do_something
end
Example:
# good
def some_method
do_something
some_num * 10
end
Example:
# good
def some_method(some_var)
do_something
some_var
end
Use tr
instead of gsub
. Open
I18n.transliterate(input).gsub(" ", "-").gsub(/[^\\dA-Za-z\-]/,"").downcase
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This cop identifies places where gsub
can be replaced by
tr
or delete
.
Example:
# bad
'abc'.gsub('b', 'd')
'abc'.gsub('a', '')
'abc'.gsub(/a/, 'd')
'abc'.gsub!('a', 'd')
# good
'abc'.gsub(/.*/, 'a')
'abc'.gsub(/a+/, 'd')
'abc'.tr('b', 'd')
'a b c'.delete(' ')
Unused method argument - context
. If it's necessary, use _
or _context
as an argument name to indicate that it won't be used. You can also write as render(*)
if you want the method to accept any arguments but don't care about them. Open
def render(context)
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This cop checks for unused method arguments.
Example:
# bad
def some_method(used, unused, _unused_but_allowed)
puts used
end
Example:
# good
def some_method(used, _unused, _unused_but_allowed)
puts used
end
Literal """Method called for each show, runs asset generators on each"""
used in void context. Open
"""Method called for each show, runs asset generators on each"""
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This cop checks for operators, variables and literals used in void context.
Example:
# bad
def some_method
some_num * 10
do_something
end
Example:
# bad
def some_method(some_var)
some_var
do_something
end
Example:
# good
def some_method
do_something
some_num * 10
end
Example:
# good
def some_method(some_var)
do_something
some_var
end
Shadowing outer local variable - venue
. Open
@collection.docs.each do |venue|
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This cop looks for use of the same name as outer local variables
for block arguments or block local variables.
This is a mimic of the warning
"shadowing outer local variable - foo" from ruby -cw
.
Example:
# bad
def some_method
foo = 1
2.times do |foo| # shadowing outer `foo`
do_something(foo)
end
end
Example:
# good
def some_method
foo = 1
2.times do |bar|
do_something(bar)
end
end
Use tr
instead of gsub
. Open
venue_name.downcase.gsub(/[^a-z0-9 -]/, '').gsub(/ /, '-').gsub('---', '-')
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This cop identifies places where gsub
can be replaced by
tr
or delete
.
Example:
# bad
'abc'.gsub('b', 'd')
'abc'.gsub('a', '')
'abc'.gsub(/a/, 'd')
'abc'.gsub!('a', 'd')
# good
'abc'.gsub(/.*/, 'a')
'abc'.gsub(/a+/, 'd')
'abc'.tr('b', 'd')
'a b c'.delete(' ')
Literal """Send a person_list to the reverse index"""
used in void context. Open
"""Send a person_list to the reverse index"""
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This cop checks for operators, variables and literals used in void context.
Example:
# bad
def some_method
some_num * 10
do_something
end
Example:
# bad
def some_method(some_var)
some_var
do_something
end
Example:
# good
def some_method
do_something
some_num * 10
end
Example:
# good
def some_method(some_var)
do_something
some_var
end
Double quote to prevent globbing and word splitting. Open
echo "DEPLOY_NAME=${PR_NUM}" >> $GITHUB_OUTPUT
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Double quote to prevent globbing and word splitting.
Problematic code:
echo $1
for i in $*; do :; done # this done and the next one also applies to expanding arrays.
for i in $@; do :; done
Correct code:
echo "$1"
for i in "$@"; do :; done # or, 'for i; do'
Rationale
The first code looks like "print the first argument". It's actually "Split the first argument by IFS (spaces, tabs and line feeds). Expand each of them as if it was a glob. Join all the resulting strings and filenames with spaces. Print the result."
The second one looks like "iterate through all arguments". It's actually "join all the arguments by the first character of IFS (space), split them by IFS and expand each of them as globs, and iterate on the resulting list". The third one skips the joining part.
Quoting variables prevents word splitting and glob expansion, and prevents the script from breaking when input contains spaces, line feeds, glob characters and such.
Strictly speaking, only expansions themselves need to be quoted, but for stylistic reasons, entire arguments with multiple variable and literal parts are often quoted as one:
$HOME/$dir/dist/bin/$file # Unquoted (bad)
"$HOME"/"$dir"/dist/bin/"$file" # Minimal quoting (good)
"$HOME/$dir/dist/bin/$file" # Canonical quoting (good)
When quoting composite arguments, make sure to exclude globs and brace expansions, which lose their special meaning in double quotes: "$HOME/$dir/src/*.c"
will not expand, but "$HOME/$dir/src"/*.c
will.
Note that $( )
starts a new context, and variables in it have to be quoted independently:
echo "This $variable is quoted $(but this $variable is not)"
echo "This $variable is quoted $(and now this "$variable" is too)"
Exceptions
Sometimes you want to split on spaces, like when building a command line:
options="-j 5 -B"
make $options file
Just quoting this doesn't work. Instead, you should have used an array (bash, ksh, zsh):
options=(-j 5 -B) # ksh: set -A options -- -j 5 -B
make "${options[@]}" file
or a function (POSIX):
make_with_flags() { make -j 5 -B "$@"; }
make_with_flags file
To split on spaces but not perform glob expansion, Posix has a set -f
to disable globbing. You can disable word splitting by setting IFS=''
.
Similarly, you might want an optional argument:
debug=""
[[ $1 == "--trace-commands" ]] && debug="-x"
bash $debug script
Quoting this doesn't work, since in the default case, "$debug"
would expand to one empty argument while $debug
would expand into zero arguments. In this case, you can use an array with zero or one elements as outlined above, or you can use an unquoted expansion with an alternate value:
debug=""
[[ $1 == "--trace-commands" ]] && debug="yes"
bash ${debug:+"-x"} script
This is better than an unquoted value because the alternative value can be properly quoted, e.g. wget ${output:+ -o "$output"}
.
As always, this warning can be [[ignore]]d on a case-by-case basis.
this is especially relevant when BASH many not be available for the array work around. For example, use in eval or in command options where script has total control of the variables...
FLAGS="-av -e 'ssh -x' --delete --delete-excluded"
...
# shellcheck disable=SC2086
eval rsync $FLAGS ~/dir remote_host:dir
Notice
Original content from the ShellCheck https://github.com/koalaman/shellcheck/wiki.
Double quote to prevent globbing and word splitting. Open
echo "DEPLOY_NAME=${REF_NAME}" >> $GITHUB_OUTPUT
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Double quote to prevent globbing and word splitting.
Problematic code:
echo $1
for i in $*; do :; done # this done and the next one also applies to expanding arrays.
for i in $@; do :; done
Correct code:
echo "$1"
for i in "$@"; do :; done # or, 'for i; do'
Rationale
The first code looks like "print the first argument". It's actually "Split the first argument by IFS (spaces, tabs and line feeds). Expand each of them as if it was a glob. Join all the resulting strings and filenames with spaces. Print the result."
The second one looks like "iterate through all arguments". It's actually "join all the arguments by the first character of IFS (space), split them by IFS and expand each of them as globs, and iterate on the resulting list". The third one skips the joining part.
Quoting variables prevents word splitting and glob expansion, and prevents the script from breaking when input contains spaces, line feeds, glob characters and such.
Strictly speaking, only expansions themselves need to be quoted, but for stylistic reasons, entire arguments with multiple variable and literal parts are often quoted as one:
$HOME/$dir/dist/bin/$file # Unquoted (bad)
"$HOME"/"$dir"/dist/bin/"$file" # Minimal quoting (good)
"$HOME/$dir/dist/bin/$file" # Canonical quoting (good)
When quoting composite arguments, make sure to exclude globs and brace expansions, which lose their special meaning in double quotes: "$HOME/$dir/src/*.c"
will not expand, but "$HOME/$dir/src"/*.c
will.
Note that $( )
starts a new context, and variables in it have to be quoted independently:
echo "This $variable is quoted $(but this $variable is not)"
echo "This $variable is quoted $(and now this "$variable" is too)"
Exceptions
Sometimes you want to split on spaces, like when building a command line:
options="-j 5 -B"
make $options file
Just quoting this doesn't work. Instead, you should have used an array (bash, ksh, zsh):
options=(-j 5 -B) # ksh: set -A options -- -j 5 -B
make "${options[@]}" file
or a function (POSIX):
make_with_flags() { make -j 5 -B "$@"; }
make_with_flags file
To split on spaces but not perform glob expansion, Posix has a set -f
to disable globbing. You can disable word splitting by setting IFS=''
.
Similarly, you might want an optional argument:
debug=""
[[ $1 == "--trace-commands" ]] && debug="-x"
bash $debug script
Quoting this doesn't work, since in the default case, "$debug"
would expand to one empty argument while $debug
would expand into zero arguments. In this case, you can use an array with zero or one elements as outlined above, or you can use an unquoted expansion with an alternate value:
debug=""
[[ $1 == "--trace-commands" ]] && debug="yes"
bash ${debug:+"-x"} script
This is better than an unquoted value because the alternative value can be properly quoted, e.g. wget ${output:+ -o "$output"}
.
As always, this warning can be [[ignore]]d on a case-by-case basis.
this is especially relevant when BASH many not be available for the array work around. For example, use in eval or in command options where script has total control of the variables...
FLAGS="-av -e 'ssh -x' --delete --delete-excluded"
...
# shellcheck disable=SC2086
eval rsync $FLAGS ~/dir remote_host:dir
Notice
Original content from the ShellCheck https://github.com/koalaman/shellcheck/wiki.
Check exit code directly with e.g. 'if mycmd;', not indirectly with $?. Open
if [[ $? != 0 ]]; then
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Check exit code directly with e.g. 'if mycmd;', not indirectly with $?.
Problematic code:
make mytarget
if [ $? -ne 0 ]
then
echo "Build failed"
fi
Correct code:
if ! make mytarget
then
echo "Build failed"
fi
Rationale:
Running a command and then checking its exit status $?
against 0 is redundant.
Instead of just checking the exit code of a command, it checks the exit code of a command (e.g. [
) that checks the exit code of a command.
Apart from the redundancy, there are other reasons to avoid this pattern:
- Since the command and its status test are decoupled, inserting an innocent command like
echo "make finished"
aftermake
will cause theif
statement to silently start comparingecho
's status instead. - Scripts that run or are called with
set -e
akaerrexit
will exit immediately if the command fails, even though they're followed by a clause that handles failure. - The value of
$?
is overwritten by[
/[[
, so you can't get the original value in the relevant then/else block (e.g.if mycmd; then echo "Success"; else echo "Failed with $?"; fi
).
To check that a command returns success, use if mycommand; then ...
.
To check that a command returns failure, use if ! mycommand; then ...
.
To additionally capture output with command substitution: if output=$(mycommand); then ...
This also applies to while
/until
loops.
Exceptions:
The default Solaris 10 bourne shell does not support '!' outside of the test command (if ! mycommand; then ...
returns !: not found
)
Notice
Original content from the ShellCheck https://github.com/koalaman/shellcheck/wiki.
Line exceeds maximum allowed length Open
# From https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort#Sorting_with_map
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Unused method argument - context
. If it's necessary, use _
or _context
as an argument name to indicate that it won't be used. You can also write as render(*)
if you want the method to accept any arguments but don't care about them. Open
def render(context)
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This cop checks for unused method arguments.
Example:
# bad
def some_method(used, unused, _unused_but_allowed)
puts used
end
Example:
# good
def some_method(used, _unused, _unused_but_allowed)
puts used
end
Literal """Add additional data to a person_list"""
used in void context. Open
"""Add additional data to a person_list"""
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- Exclude checks
This cop checks for operators, variables and literals used in void context.
Example:
# bad
def some_method
some_num * 10
do_something
end
Example:
# bad
def some_method(some_var)
some_var
do_something
end
Example:
# good
def some_method
do_something
some_num * 10
end
Example:
# good
def some_method(some_var)
do_something
some_var
end
Unused block argument - site
. You can omit the argument if you don't care about it. Open
Jekyll::Hooks.register :site, :after_init do |site|
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- Exclude checks
This cop checks for unused block arguments.
Example:
# bad
do_something do |used, unused|
puts used
end
do_something do |bar|
puts :foo
end
define_method(:foo) do |bar|
puts :baz
end
Example:
#good
do_something do |used, _unused|
puts used
end
do_something do
puts :foo
end
define_method(:foo) do |_bar|
puts :baz
end
Unused block argument - site
. You can omit the argument if you don't care about it. Open
Jekyll::Hooks.register :site, :post_write do |site|
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- Exclude checks
This cop checks for unused block arguments.
Example:
# bad
do_something do |used, unused|
puts used
end
do_something do |bar|
puts :foo
end
define_method(:foo) do |bar|
puts :baz
end
Example:
#good
do_something do |used, _unused|
puts used
end
do_something do
puts :foo
end
define_method(:foo) do |_bar|
puts :baz
end
Literal """Return the two character representation of the year span as a list"""
used in void context. Open
"""Return the two character representation of the year span as a list"""
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- Exclude checks
This cop checks for operators, variables and literals used in void context.
Example:
# bad
def some_method
some_num * 10
do_something
end
Example:
# bad
def some_method(some_var)
some_var
do_something
end
Example:
# good
def some_method
do_something
some_num * 10
end
Example:
# good
def some_method(some_var)
do_something
some_var
end
Unused block argument - city
. If it's necessary, use _
or _city
as an argument name to indicate that it won't be used. Open
site.data['venues_by_city'].each do |city, venues|
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- Exclude checks
This cop checks for unused block arguments.
Example:
# bad
do_something do |used, unused|
puts used
end
do_something do |bar|
puts :foo
end
define_method(:foo) do |bar|
puts :baz
end
Example:
#good
do_something do |used, _unused|
puts used
end
do_something do
puts :foo
end
define_method(:foo) do |_bar|
puts :baz
end
Useless assignment to variable - show_crew_count
. Open
show_crew_count = show.data["crew"] ? show.data["crew"].length : 0
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This cop checks for every useless assignment to local variable in every
scope.
The basic idea for this cop was from the warning of ruby -cw
:
assigned but unused variable - foo
Currently this cop has advanced logic that detects unreferenced reassignments and properly handles varied cases such as branch, loop, rescue, ensure, etc.
Example:
# bad
def some_method
some_var = 1
do_something
end
Example:
# good
def some_method
some_var = 1
do_something(some_var)
end
Line exceeds maximum allowed length Open
ret += "<tr class=\"album-row\" data-key=\"#{ album["AlbumKey"] }\"><td><a href=\"#{ album['WebUri'] }\" class=\"usage-link\">#{ album["Name"] }</a></td><td>#{ album["AlbumKey"] }</td><td>#{ album["ImageCount"] }</td><td class=\"usage\">?</td></tr>\n"
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