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Detector Library

Shell detectors (173/173)

Ineffective Variable Assignment End token not found Invalid ShellCheck Directive Placement Variable Assignment Syntax SSH Stdin Interference Glob Pattern Safety Sensitive bourne shells Avoid LS-Grep Unrecognized shebang Shebang Mismatch String Length Calculation Unicode Dash In Command Ensure no spaces are used Grouping expressions Single quotes strictly terminate Unnecessary Single Quotes Leading Zero Arithmetic Backslash followed by a linefeed Use of terminate commands Missing exec Terminator Incorrect Tick Usage Semicolons directly after else Array Element Separation Apostrophe terminated single quoted string Invalid Unary Test Operator Sudo Redirect Misuse Shebang Placement Incorrectly used escape sequences Improper use of curly braces Missing Space Before Colon Printf Variable Interpolation Pipeline Assignment Syntax Non Portable Character Class Here-Document Command Terminator Placement Test operator missing an operand Expr Modernization Missing Function Opening Brace Missing Space Before Comment Arithmetic Expression Syntax Reversed Shebang Command Substitution Execution Unsupported Decimal Comparison Semicolons directly after then ShellCheck Directive Placement Missing Space After Function Name Unquoted Regex Matching Missing Space Before Negation Redirection Misinterpretation Unexpected Directive Unquoted Special Parameters Command Expansion Error Do not use unicode non-breaking space Unnecessary Brackets In Tr Unquoted Command Substitution Incorrect Redirection Order Unexpected opening parenthesis Incorrect Regex Operator Unicode Quote Usage Single-Iteration Loop Integer Division Precision Loss File Read-Write Race Condition Unable To Follow Source Invalid Parentheses Usage Trailing Space After Backslash Shebang Syntax Correction Unquoted tr Arguments Use shell logical operators Incorrect Command Substitution in Find Exec Non-empty then clause Incorrect Comment Syntax Suspicious End Quote Directive Comment Syntax Unmatched Keyword Unbraced Array Expansion Prefer Find Over LS Missing Do Keyword Then after if statement Invalid Test Operator Usage Unquoted Ampersand in Command Null-Terminated Filename Handling Function in External Command Avoid Complex Logical Expressions Unquoted RHS Comparison Incorrect Keyword Capitalization Unquoted Array Expansion Test Bracket Termination Unnecessary Exec Command Document is not properly terminated Constant Comparison Sensitive whitespace of bourne shells Avoid escaping parentheses Tr Misused For Word Replacement Incorrect Logical Operator Bracket Spacing in Conditional Statements Command Assignment Incorrect Numeric Comparison Unquoted Eval Argument Here-doc Whitespace Useless Cat Elimination UTF-8 BOM Present Glob-based Iteration PS Grep Alternative Glob Matching in Test Brackets Unnecessary Dollar In For Loop Here-Document End Token Isolation Dollar should be escaped with a backslash Unnecessary Quoting in Loop Here-doc Comment Only literals can be escaped Unquoted Grep Patterns Find Print Zero Usage Misused Regex Operator Incorrect Branching Keyword Invalid unary test operator usage Detects if statement without terminator Unquoted Find Patterns Unexpected Redirection in Comparison Shells are space sensitive Process only removes tabs Missing Spaces in Comparison Misplaced Line Continuation Operator POSIX Shell Compatibility Arithmetic Expansion Command Execution Shell Prompt Escape Sequences Echo Escape Sequences Command Argument Handling Brace Expansion Limitation Escape Dollar Sign in Quotes Parsing Error Braces required for positionals Unnecessary Backslash Escape Non Constant Source Variable Indirection Tilde Expansion Unnecessary Variable Expansion Use of if and then Incorrect Equality Operator Unescaped Variable in Remote Command Unnecessary Echo Pipe Keywords being used as arguments Unescaped Variable Find Loop Safety Read Lines with While Loop Unclosed String Unclosed Do Statement Misplaced ShellCheck Directive Regex Asterisk Misuse Source Parsing Failed Backtick Command Injection Unnecessary Echo Unintended Literal Brace Incorrect Function Parameter Declaration Multi-Parameter Shebang Subshell Variable Modification Shell Alias Nesting Here-Doc Termination Linefeed Incorrect Grep Pattern Remove indentation before end token Syntax Error Detection Incorrect Conditional Syntax Remove Leading Spaces Before Shebang Unsupported Script Language Incorrect Quoting in Trap Commands Missing Dollar Sign Missing Shebang Premature Variable Expansion Unquoted Variable in Test Here Document Expansion Control Arithmetic Expansion Modernization Dollar Sign In Assignment Unused Variable Detection Command Substitution Syntax Parameter Expansion for String Manipulation

Low

Showing all detectors for the Shell language with low severity.

Invalid ShellCheck Directive Placement

ShellCheck directives incorrectly placed within case statement branches.

Unrecognized shebang

Unrecognized shebang, Tool supports only 'sh/bash/dash/ksh'. Add a 'shell' directive.

String Length Calculation

Use ${#variable} for efficient string length calculation.

Single quotes strictly terminate

In POSIX shell, single quotes strictly terminate quoted segments without interpreting any characters within.

Unnecessary Single Quotes

Use double quotes instead of single quotes for variable expansion in shell scripts.

Backslash followed by a linefeed

Single-quoted strings treat backslash followed by a linefeed as a literal backslash and linefeed, with no special meaning.

Use of terminate commands

Use either '&' or ';' to terminate commands, but not both.

Incorrect Tick Usage

Incorrect tick character usage.

Non Portable Character Class

Shell script uses non-portable character ranges instead of POSIX character classes for case conversion.

Missing Space Before Comment

Shell script contains a comment without a preceding space, potentially causing syntax errors.

Unnecessary Brackets In Tr

Shell script incorrectly uses square brackets around character ranges in tr command.

Unicode Quote Usage

Presence of Unicode quotes instead of ASCII quotes.

Integer Division Precision Loss

Shell script performs integer division before multiplication, potentially losing precision in calculations.

Unable To Follow Source

ShellCheck unable to analyze sourced file due to access issues or configuration.

Trailing Space After Backslash

Shell script contains trailing spaces after a backslash used for line continuation, causing syntax errors.

Incorrect Comment Syntax

Use correct comment syntax.

Unbraced Array Expansion

Shell script uses unbraced syntax for array expansion, potentially leading to incorrect interpretation.

Avoid Complex Logical Expressions

Don't use' A && B || C' as a substitute for if-then-else constructs.

Avoid escaping parentheses

Avoid escaping parentheses inside square bracket expressions.

Tr Misused For Word Replacement

Shell script incorrectly uses tr command to replace words instead of individual characters.

Bracket Spacing in Conditional Statements

Proper spacing before opening brackets in shell conditional statements.

Useless Cat Elimination

Avoid unnecessary use of 'cat' for single file input.

Unnecessary Dollar In For Loop

For loop in shell script incorrectly uses $ on the iterator variable name.

Dollar should be escaped with a backslash

In double quotes, $ is special but can be interpreted literally in specific contexts; use a backslash to escape it when intended as literal.

Only literals can be escaped

Incorrect escape sequences are ignored, use a literal backslash, single quote, or correct escape method.

Process only removes tabs

The process only removes tabs, not spaces, but your editor might convert tabs to spaces automatically.

Shell Prompt Escape Sequences

Shell prompt uses unescaped escape sequences, leading to display issues.

Echo Escape Sequences

Shell script uses echo to print escape sequences, which doesn't work as intended.

Escape Dollar Sign in Quotes

Use backslash to escape $ within quotes instead of ending quotes.

Unnecessary Backslash Escape

Avoid unnecessary backslash escapes.

Non Constant Source

Shell script uses a non-constant source path, which can't be statically analyzed for potential issues.

Tilde Expansion

Use '$HOME' instead of tilde in quotes.

Unnecessary Variable Expansion

Avoid unnecessary dollar signs in arithmetic expressions.

Unnecessary Echo Pipe

Piping to 'echo' command incorrectly.

Unescaped Variable

Shell script incorrectly uses unescaped quotes within a string, causing syntax errors.

Misplaced ShellCheck Directive

ShellCheck directives incorrectly placed after commands.

Regex Asterisk Misuse

Shell script misuses asterisk in regex, potentially leading to unintended matches.

Unnecessary Echo

Remove unnecessary 'echo' when outputting command results.

Unsupported Script Language

Identifying scripts written in languages not supported by ShellCheck.

Unused Variable Detection

Variable appears unused in the script.

Parameter Expansion for String Manipulation

Use parameter expansion instead of 'sed' for simple string replacements.