ShellCheck codes supported by BashSupport Pro

These are all checks of ShellCheck supported by BashSupport Pro. Please refer to the manual page about ShellCheck to learn more about the available features.

Our Bash IDE supports highlighting of ShellCheck messages in the editor, suppression with # shellcheck comments, tooltips on codes like SC1000 and more. Please note, that the description were taken from the official ShellCheck wiki and the copyright of the English messages belongs to ShellCheck project, of course.

SC1000: $ is not used specially and should therefore be escaped.

SC1001: This \o will be a regular 'o' in this context.

SC1003: Want to escape a single quote? echo 'This is how it'\''s done'.

SC1004: This backslash+linefeed is literal. Break outside single quotes if you just want to break the line.

SC1007: Remove space after = if trying to assign a value (or for empty string, use var='' ... ).

SC1008: This shebang was unrecognized. ShellCheck only supports sh/bash/dash/ksh. Add a 'shell' directive to specify.

SC1009: The mentioned parser error was in ...

SC1010: Use semicolon or linefeed before done (or quote to make it literal).

SC1011: This apostrophe terminated the single quoted string!

SC1012: \t is just literal t here. For tab, use "$(printf '\t')" instead.

SC1014: Use if cmd; then .. to check exit code, or if [ "$(cmd)" = .. ] to check output.

SC1015: This is a unicode double quote. Delete and retype it.

SC1016: This is a Unicode single quote. Delete and retype it.

SC1017: Literal carriage return. Run script through tr -d '\r' .

SC1018: This is a unicode non-breaking space. Delete it and retype as space.

SC1019: Expected this to be an argument to the unary condition.

SC1020: You need a space before the ] or ]]

SC1026: If grouping expressions inside [[..]], use ( .. ).

SC1027: Expected another argument for this operator.

SC1028: In [..] you have to escape  or preferably combine [..] expressions.

SC1029: In [[..]] you shouldn't escape ( or ).

SC1033: Test expression was opened with double [[ but closed with single ]. Make sure they match.

SC1034: Test expression was opened with double [ but closed with single ]]. Make sure they match.

SC1035: You need a space here

SC1036: ( is invalid here. Did you forget to escape it?

SC1037: Braces are required for positionals over 9, e.g. ${10}.

SC1038: Shells are space sensitive. Use < <(cmd), not <<(cmd).

SC1039: Remove indentation before end token (or use <<- and indent with tabs).

SC1040: When using <<-, you can only indent with tabs.

SC1041: Found eof further down, but not on a separate line.

SC1042: Close matches include -eof (!= eof).

SC1043: Found EOF further down, but with wrong casing.

SC1044: Couldn't find end token EOF in the here document.

SC1045: It's not foo &; bar, just foo & bar.

SC1046: Couldn't find fi for this if.

SC1047: Expected fi matching previously mentioned if.

SC1048: Can't have empty then clauses (use true as a no-op).

SC1049: Did you forget the then for this if?

SC1050: Expected then.

SC1051: Semicolons directly after then are not allowed. Just remove it.

SC1052: Semicolons directly after then are not allowed. Just remove it.

SC1053: Semicolons directly after else are not allowed. Just remove it.

SC1054: You need a space after the {.

SC1055: You need at least one command here. Use true; as a no-op.

SC1056: Expected a }. If you have one, try a ; or \n in front of it.

SC1057: Did you forget the do for this loop?

SC1058: Expected do.

SC1059: Semicolon is not allowed directly after do. You can just delete it.

SC1060: Can't have empty do clauses (use true as a no-op)

SC1061: Couldn't find done for this do.

SC1062: Expected done matching previously mentioned do.

SC1063: You need a line feed or semicolon before the do.

SC1064: Expected a { to open the function definition.

SC1065: Trying to declare parameters? Don't. Use () and refer to params as $1, $2, ..

SC1066: Don't use $ on the left side of assignments.

SC1067: For indirection, use arrays, declare "var$n=value", or (for sh) read/eval

SC1068: Don't put spaces around the = in assignments.

SC1069: You need a space before the [.

SC1070: Parsing stopped here. Mismatched keywords or invalid parentheses?

SC1071: ShellCheck only supports sh/bash/dash/ksh scripts. Sorry!

SC1072: Unexpected ..

SC1073: Couldn't parse this (thing). Fix to allow more checks.

SC1074: Did you forget the ;; after the previous case item?

SC1075: Use elif instead of else if.

SC1076: Trying to do math? Use e.g. [ $((i/2+7)) -ge 18 ].

SC1077: For command expansion, the tick should slant left (` vs ´).

SC1078: Did you forget to close this double quoted string?

SC1079: This is actually an end quote, but due to next char it looks suspect.

SC1080: You need \ before line feeds to break lines in [ ].

SC1081: Scripts are case-sensitive. Use if, not If.

SC1082: This file has a UTF-8 BOM. Remove it with: LC_CTYPE=C sed '1s/^...//' < yourscript.

SC1083: This {/} is literal. Check if ; is missing or quote the expression.

SC1084: Use #!, not !#, for the shebang.

SC1086: Don't use $ on the iterator name in for loops.

SC1087: Use braces when expanding arrays, e.g. ${array[idx]} (or ${var}[.. to quiet).

SC1088: Parsing stopped here. Invalid use of parentheses?

SC1089: Parsing stopped here. Is this keyword correctly matched up?

SC1090: Can't follow non-constant source. Use a directive to specify location.

SC1091: Not following: (error message here)

SC1092: Stopping at 100 source frames :O

SC1094: Parsing of sourced file failed. Ignoring it.

SC1095: You need a space or linefeed between the function name and body.

SC1097: Unexpected ==. For assignment, use =. For comparison, use [/[[.

SC1098: Quote/escape special characters when using eval, e.g. eval "a=(b)".

SC1099: You need a space before the #.

SC1100: This is a unicode dash. Delete and retype as ASCII minus.

SC1101: Delete trailing spaces after \ to break line (or use quotes for literal space).

SC1102: Shells disambiguate $(( differently or not at all. For $(command substitution), add space after $( . For $((arithmetics)), fix parsing errors.

SC1103: This shell type is unknown. Use e.g. sh or bash.

SC1104: Use #!, not just !, for the shebang.

SC1105: Shells disambiguate (( differently or not at all. If the first ( should start a subshell, add a space after it.

SC1106: In arithmetic contexts, use < instead of -lt

SC1107: This directive is unknown. It will be ignored.

SC1108: You need a space before and after the = .

SC1109: This is an unquoted HTML entity. Replace with corresponding character.

SC1110: This is a unicode quote. Delete and retype it (or quote to make literal).

SC1111: This is a unicode quote. Delete and retype it (or ignore/singlequote for literal).

SC1112: This is a unicode quote. Delete and retype it (or ignore/doublequote for literal).

SC1113: Use #!, not just #, for the shebang.

SC1114: Remove leading spaces before the shebang.

SC1115: Remove spaces between # and ! in the shebang.

SC1116: Missing $ on a $((..)) expression? (or use ( ( for arrays).

SC1117: Backslash is literal in "\n". Prefer explicit escaping: "\\n".

SC1118: Delete whitespace after the here-doc end token.

SC1119: Add a linefeed between end token and terminating ).

SC1120: No comments allowed after here-doc token. Comment the next line instead.

SC1121: Add ;/& terminators (and other syntax) on the line with the <<, not here.

SC1122: Nothing allowed after end token. To continue a command, put it on the line with the <<.

SC1123: ShellCheck directives are only valid in front of complete compound commands, like if, not e.g. individual elif branches.

SC1124: ShellCheck directives are only valid in front of complete commands like case statements, not individual case branches.

SC1125: Invalid key=value pair in directive

SC1126: Place shellcheck directives before commands, not after.

SC1127: Was this intended as a comment? Use # in sh.

SC1128: The shebang must be on the first line. Delete blanks and move comments.

SC1129: You need a space before the !.

SC1130: You need a space before the :.

SC1131: Use elif to start another branch.

SC1132: This & terminates the command. Escape it or add space after & to silence.

SC1133: Unexpected start of line. If breaking lines, |/||/&& should be at the end of the previous one.

SC1134: Error parsing shellcheckrc:

SC1135: Prefer escape over ending quote to make $ literal. Instead of "It costs $"5, use "It costs \$5"

SC1136: Unexpected characters after terminating ]. Missing semicolon/linefeed?

SC1137: Missing second ( to start arithmetic for ((;;)) loop

SC1138: Shells are space sensitive. Use < <(cmd), not << (cmd).

SC1139: Use || instead of -o between test commands.

SC1140: Unexpected parameters after condition. Missing &&/||, or bad expression?

SC1141: Unexpected tokens after compound command. Bad redirection or missing ;/&&/||/|?

SC1142: Use done < <(cmd) to redirect from process substitution (currently missing one <).

SC1143: This backslash is part of a comment and does not continue the line.

SC1144: external-sources can only be enabled in .shellcheckrc, not in individual files.

SC1145: Unknown external-sources value. Expected true/false.

SC2000: See if you can use ${#variable} instead

SC2001: See if you can use ${variable//search/replace} instead.

SC2002: Useless cat. Consider cmd < file | .. or cmd file | .. instead.

SC2003: expr is antiquated. Consider rewriting this using $((..)), ${} or [[ ]].

SC2004: $/${} is unnecessary on arithmetic variables.

SC2005: Useless echo? Instead of echo $(cmd), just use cmd

SC2006: Use $(...) notation instead of legacy backticked `...`.

SC2007: Use $((..)) instead of deprecated $[..].

SC2008: echo doesn't read from stdin, are you sure you should be piping to it?

SC2009: Consider using pgrep instead of grepping ps output.

SC2010: Don't use ls | grep. Use a glob or a for loop with a condition to allow non-alphanumeric filenames.

SC2011: Use find -print0 or find -exec to better handle non-alphanumeric filenames.

SC2012: Use find instead of ls to better handle non-alphanumeric filenames.

SC2013: To read lines rather than words, pipe/redirect to a while read loop.

SC2014: This will expand once before find runs, not per file found.

SC2015: Note that A && B || C is not if-then-else. C may run when A is true.

SC2016: Expressions don't expand in single quotes, use double quotes for that.

SC2017: Increase precision by replacing a/b*c with a*c/b.

SC2018: Use [:lower:] to support accents and foreign alphabets.

SC2019: Use [:upper:] to support accents and foreign alphabets.

SC2020: tr replaces sets of chars, not words (mentioned due to duplicates).

SC2021: Don't use [] around ranges in tr, it replaces literal square brackets.

SC2022: Note that unlike globs, o* here matches ooo but not oscar.

SC2023: The shell may override time as seen in man time(1). Use command time .. for that one.

SC2024: sudo doesn't affect redirects. Use ..| sudo tee file

SC2025: Make sure all escape sequences are enclosed in \[..\] to prevent line wrapping issues.

SC2026: This word is outside of quotes. Did you intend to 'nest '"'single quotes'"' instead'?

SC2027: The surrounding quotes actually unquote this. Remove or escape them.

SC2028: echo won't expand escape sequences. Consider printf.

SC2029: Note that, unescaped, this expands on the client side.

SC2030: Modification of var is local (to subshell caused by pipeline).

SC2031: var was modified in a subshell. That change might be lost.

SC2032: This function can't be invoked via su on line 42.

SC2033: Shell functions can't be passed to external commands. Use separate script or sh -c.

SC2034: foo appears unused. Verify it or export it.

SC2035: Use ./*glob* or -- *glob* so names with dashes won't become options.

SC2036: If you wanted to assign the output of the pipeline, use a=$(b | c) .

SC2037: To assign the output of a command, use var=$(cmd) .

SC2038: Use -print0/-0 or find -exec + to allow for non-alphanumeric filenames.

SC2039: In POSIX sh, *something* is undefined.

SC2040: #!/bin/sh was specified, so ____ is not supported, even when sh is actually bash.

SC2041: This is a literal string. To run as a command, use $(..) instead of '..' .

SC2042: Use spaces, not commas, to separate loop elements.

SC2043: This loop will only ever run once for a constant value. Did you perhaps mean to loop over dir/*, $var or $(cmd)?

SC2044: For loops over find output are fragile. Use find -exec or a while read loop.

SC2045: Iterating over ls output is fragile. Use globs.

SC2046: Quote this to prevent word splitting.

SC2048: Use "$@" (with quotes) to prevent whitespace problems.

SC2049: =~ is for regex, but this looks like a glob. Use = instead.

SC2050: This expression is constant. Did you forget the $ on a variable?

SC2051: Bash doesn't support variables in brace range expansions.

SC2053: Quote the rhs of = in [[ ]] to prevent glob matching.

SC2054: Use spaces, not commas, to separate array elements.

SC2055: You probably wanted && here, otherwise it's always true.

SC2056: You probably wanted && here

SC2057: Unknown binary operator.

SC2058: Unknown unary operator.

SC2059: Don't use variables in the printf format string. Use printf "..%s.." "$foo".

SC2060: Quote parameters to tr to prevent glob expansion.

SC2061: Quote the parameter to -name so the shell won't interpret it.

SC2062: Quote the grep pattern so the shell won't interpret it.

SC2063: Grep uses regex, but this looks like a glob.

SC2064: Use single quotes, otherwise this expands now rather than when signalled.

SC2065: This is interpreted as a shell file redirection, not a comparison.

SC2066: Since you double quoted this, it will not word split, and the loop will only run once.

SC2067: Missing ; or + terminating -exec. You can't use |/||/&&, and ; has to be a separate, quoted argument.

SC2068: Double quote array expansions to avoid re-splitting elements.

SC2069: To redirect stdout+stderr, 2>&1 must be last (or use { cmd > file; } 2>&1 to clarify).

SC2070: -n doesn't work with unquoted arguments. Quote or use [[ ]].

SC2071: > is for string comparisons. Use -gt instead.

SC2072: Decimals are not supported. Either use integers only, or use bc or awk to compare.

SC2073: Escape \< to prevent it redirecting (or switch to [[ .. ]]).

SC2074: Can't use =~ in [ ]. Use [[..]] instead.

SC2075: Escaping \< is required in [..], but invalid in [[..]]

SC2076: Don't quote rhs of =~, it'll match literally rather than as a regex.

SC2077: You need spaces around the comparison operator.

SC2078: This expression is constant. Did you forget a $ somewhere?

SC2079: (( )) doesn't support decimals. Use bc or awk.

SC2080: Numbers with leading 0 are considered octal.

SC2081: [ .. ] can't match globs. Use [[ .. ]] or grep.

SC2082: To expand via indirection, use name="foo$n"; echo "${!name}".

SC2083: Don't add spaces after the slash in ./file.

SC2084: Remove $ or use _=$((expr)) to avoid executing output.

SC2086: Double quote to prevent globbing and word splitting.

SC2087: Quote EOF to make here document expansions happen on the server side rather than on the client.

SC2088: Tilde does not expand in quotes. Use $HOME.

SC2089: Quotes/backslashes will be treated literally. Use an array.

SC2090: Quotes/backslashes in this variable will not be respected.

SC2091: Remove surrounding $() to avoid executing output (or use eval if intentional).

SC2092: Remove backticks to avoid executing output.

SC2093: Remove exec if script should continue after this command.

SC2094: Make sure not to read and write the same file in the same pipeline.

SC2095: Use ssh -n to prevent ssh from swallowing stdin.

SC2096: On most OS, shebangs can only specify a single parameter.

SC2097: This assignment is only seen by the forked process.

SC2098: This expansion will not see the mentioned assignment.

SC2099: Use $((..)) for arithmetics, e.g. i=$((i + 2))

SC2100: Use $((..)) for arithmetics, e.g. i=$((i + 2))

SC2101: Named class needs outer [], e.g. [[:digit:]].

SC2102: Ranges can only match single chars (mentioned due to duplicates).

SC2103: Use a ( subshell ) to avoid having to cd back.

SC2104: In functions, use return instead of break.

SC2105: break is only valid in loops

SC2106: This only exits the subshell caused by the pipeline.

SC2107: Instead of [ a && b ], use [ a ] && [ b ].

SC2108: In [[..]], use && instead of -a.

SC2109: Instead of [ a || b ], use [ a ] || [ b ].

SC2110: In [[..]], use || instead of -o.

SC2111: ksh does not allow function keyword and () at the same time.

SC2112: function keyword is non-standard. Delete it.

SC2113: function keyword is non-standard. Use foo() instead of function foo.

SC2114: Warning: deletes a system directory.

SC2115: Use "${var:?}" to ensure this never expands to /* .

SC2116: Useless echo? Instead of cmd $(echo foo), just use cmd foo.

SC2117: To run commands as another user, use su -c or sudo.

SC2118: Ksh does not support |&. Use 2>&1 |

SC2119: Use foo "$@" if function's $1 should mean script's $1.

SC2120: foo references arguments, but none are ever passed.

SC2121: To assign a variable, use just var=value, not set ...

SC2122: >= is not a valid operator. Use ! a < b instead.

SC2123: PATH is the shell search path. Use another name.

SC2124: Assigning an array to a string! Assign as array, or use * instead of @ to concatenate.

SC2125: Brace expansions and globs are literal in assignments. Quote it or use an array.

SC2126: Consider using grep -c instead of grep | wc

SC2127: To use ${ ..; }, specify #!/usr/bin/env ksh.

SC2128: Expanding an array without an index only gives the first element.

SC2129: Consider using { cmd1; cmd2; } >> file instead of individual redirects.

SC2130: -eq is for integer comparisons. Use = instead.

SC2139: This expands when defined, not when used. Consider escaping.

SC2140: Word is of the form "A"B"C" (B indicated). Did you mean "ABC" or "A\\"B\\"C"?

SC2141: Did you mean IFS=$'\t' ?

SC2142: Aliases can't use positional parameters. Use a function.

SC2143: Use grep -q instead of comparing output with [ -n .. ].

SC2144: -e doesn't work with globs. Use a for loop.

SC2145: Argument mixes string and array. Use * or separate argument.

SC2146: This action ignores everything before the -o. Use  to group.

SC2147: Literal tilde in PATH works poorly across programs.

SC2148: Tips depend on target shell and yours is unknown. Add a shebang.

SC2149: Remove $/${} for numeric index, or escape it for string.

SC2150: -exec does not automatically invoke a shell. Use -exec sh -c .. for that.

SC2151: Only one integer 0-255 can be returned. Use stdout for other data.

SC2152: Can only return 0-255. Other data should be written to stdout.

SC2153: Possible Misspelling: MYVARIABLE may not be assigned. Did you mean MY_VARIABLE?

SC2154: var is referenced but not assigned.

SC2155: Declare and assign separately to avoid masking return values.

SC2156: Injecting filenames is fragile and insecure. Use parameters.

SC2157: Argument to implicit -n is always true due to literal strings.

SC2158: [ false ] is true. Remove the brackets

SC2159: [ 0 ] is true. Use false instead.

SC2160: Instead of [ true ], just use true.

SC2161: Instead of [ 1 ], use true.

SC2162: read without -r will mangle backslashes.

SC2163: This does not export FOO. Remove $/${} for that, or use ${var?} to quiet.

SC2164: Use cd ... || exit in case cd fails.

SC2165: This nested loop overrides the index variable of its parent.

SC2166: Prefer [ p ] && [ q ] as [ p -a q ] is not well defined.

SC2167: This parent loop has its index variable overridden.

SC2168: local is only valid in functions.

SC2169: In dash, *something* is not supported.

SC2170: Invalid number for -eq. Use = to compare as string (or use $var to expand as a variable).

SC2171: Found trailing ] outside test. Add missing [ or quote if intentional.

SC2172: Trapping signals by number is not well defined. Prefer signal names.

SC2173: SIGKILL/SIGSTOP can not be trapped.

SC2174: When used with -p, -m only applies to the deepest directory.

SC2175: Quote this invalid brace expansion since it should be passed literally to eval

SC2176: time is undefined for pipelines. time single stage or bash -c instead.

SC2177: time is undefined for compound commands, use time sh -c instead.

SC2178: Variable was used as an array but is now assigned a string.

SC2179: Use array+=("item") to append items to an array.

SC2180: Bash does not support multidimensional arrays. Use 1D or associative arrays.

SC2181: Check exit code directly with e.g. if mycmd;, not indirectly with $?.

SC2182: This printf format string has no variables. Other arguments are ignored.

SC2183: This format string has 2 variables, but is passed 1 arguments.

SC2184: Quote arguments to unset so they're not glob expanded.

SC2185: Some finds don't have a default path. Specify . explicitly.

SC2186: tempfile is deprecated. Use mktemp instead.

SC2187: Ash scripts will be checked as Dash. Add # shellcheck shell=dash to silence.

SC2188: This redirection doesn't have a command. Move to its command (or use true as no-op).

SC2189: You can't have | between this redirection and the command it should apply to.

SC2190: Elements in associative arrays need index, e.g. array=( [index]=value ) .

SC2191: The = here is literal. To assign by index, use ( [index]=value ) with no spaces. To keep as literal, quote it.

SC2192: This array element has no value. Remove spaces after = or use "" for empty string.

SC2193: The arguments to this comparison can never be equal. Make sure your syntax is correct.

SC2194: This word is constant. Did you forget the $ on a variable?

SC2195: This pattern will never match the case statement's word. Double check them.

SC2196: egrep is non-standard and deprecated. Use grep -E instead.

SC2197: fgrep is non-standard and deprecated. Use grep -F instead.

SC2198: Arrays don't work as operands in [ ]. Use a loop (or concatenate with * instead of @).

SC2199: Arrays implicitly concatenate in [[ ]]. Use a loop (or explicit * instead of @).

SC2200: Brace expansions don't work as operands in [ ]. Use a loop.

SC2201: Brace expansion doesn't happen in [[ ]]. Use a loop.

SC2202: Globs don't work as operands in [ ]. Use a loop.

SC2203: Globs are ignored in [[ ]] except right of =/!=. Use a loop.

SC2204: (..) is a subshell. Did you mean [ .. ], a test expression?

SC2205: (..) is a subshell. Did you mean [ .. ], a test expression?

SC2206: Quote to prevent word splitting/globbing, or split robustly with mapfile or read -a.

SC2207: Prefer mapfile or read -a to split command output (or quote to avoid splitting).

SC2208: Use [[ ]] or quote arguments to -v to avoid glob expansion.

SC2209: Use var=$(command) to assign output (or quote to assign string).

SC2210: This is a file redirection. Was it supposed to be a comparison or fd operation?

SC2211: This is a glob used as a command name. Was it supposed to be in ${..}, array, or is it missing quoting?

SC2212: Use false instead of empty [/[[ conditionals.

SC2213: getopts specified -n, but it's not handled by this case.

SC2214: This case is not specified by getopts.

SC2215: This flag is used as a command name. Bad line break or missing [ .. ]?

SC2216: Piping to rm, a command that doesn't read stdin. Wrong command or missing xargs?

SC2217: Redirecting to echo, a command that doesn't read stdin. Bad quoting or missing xargs?

SC2218: This function is only defined later. Move the definition up.

SC2219: Instead of let expr, prefer (( expr )) .

SC2220: Invalid flags are not handled. Add a *) case.

SC2221: This pattern always overrides a later one.

SC2222: This pattern never matches because of a previous pattern.

SC2223: This default assignment may cause DoS due to globbing. Quote it.

SC2224: This mv has no destination. Check the arguments.

SC2225: This cp has no destination. Check the arguments.

SC2226: This ln has no destination. Check the arguments, or specify . explicitly.

SC2227: Redirection applies to the find command itself. Rewrite to work per action (or move to end).

SC2229: This does not read foo. Remove $/${} for that, or use ${var?} to quiet.

SC2230: which is non-standard. Use builtin command -v instead.

SC2231: Quote expansions in this for loop glob to prevent wordsplitting, e.g. "$dir"/*.txt .

SC2232: Can't use sudo with builtins like cd. Did you want sudo sh -c .. instead?

SC2233: Remove superfluous (..) around condition to avoid subshell overhead.

SC2234: Remove superfluous (..) around test command to avoid subshell overhead.

SC2235: Use { ..; } instead of (..) to avoid subshell overhead.

SC2236: Use -n instead of ! -z.

SC2237: Use [ -n .. ] instead of ! [ -z .. ].

SC2238: Redirecting to/from command name instead of file. Did you want pipes/xargs (or quote to ignore)?

SC2239: Ensure the shebang uses the absolute path to the interpreter.

SC2240: The dot command does not support arguments in sh/dash. Set them as variables.

SC2241: The exit status can only be one integer 0-255. Use stdout for other data.

SC2242: Can only exit with status 0-255. Other data should be written to stdout/stderr.

SC2243: Prefer explicit -n to check for output (or run command without [/[[ to check for success)

SC2244: Prefer explicit -n to check non-empty string (or use =/-ne to check boolean/integer).

SC2245: -d only applies to the first expansion of this glob. Use a loop to check any/all.

SC2246: This shebang specifies a directory. Ensure the interpreter is a file.

SC2247: Flip leading $ and " if this should be a quoted substitution.

SC2248: Prefer double quoting even when variables don't contain special characters.

SC2249: Consider adding a default *) case, even if it just exits with error.

SC2250: Prefer putting braces around variable references even when not strictly required.

SC2251: This ! is not on a condition and skips errexit. Use && exit 1 instead, or make sure $? is checked.

SC2252: You probably wanted && here, otherwise it's always true.

SC2253: Use -R to recurse, or explicitly a-r to remove read permissions.

SC2254: Quote expansions in case patterns to match literally rather than as a glob.

SC2255: [ ] does not apply arithmetic evaluation. Evaluate with $((..)) for numbers, or use string comparator for strings.

SC2256: This translated string is the name of a variable. Flip leading $ and " if this should be a quoted substitution.

SC2257: Arithmetic modifications in command redirections may be discarded. Do them separately.

SC2259: This redirection overrides piped input. To use both, merge or pass filenames.

SC2260: This redirection overrides the output pipe. Use tee to output to both.

SC2261: Multiple redirections compete for stdout. Use cat, tee, or pass filenames instead.

SC2262: This alias can't be defined and used in the same parsing unit. Use a function instead.

SC2263: Since they're in the same parsing unit, this command will not refer to the previously mentioned alias.

SC2264: This function unconditionally re-invokes itself. Missing command?

SC2265: Use && for logical AND. Single & will background and return true.

SC2266: Use && for logical AND. Single & will background and return true.

SC2267: GNU xargs -i is deprecated in favor of -I{}

SC2268: Avoid x-prefix in comparisons as it no longer serves a purpose.

SC2269: This variable is assigned to itself, so the assignment does nothing.

SC2270: To assign positional parameters, use set -- first second .. (or use [ ] to compare).

SC2271: For indirection, use arrays, declare "var$n=value", or (for sh) read/eval

SC2272: Command name contains ==. For comparison, use [ "$var" = value ].

SC2273: Sequence of ===s found. Merge conflict or intended as a commented border?

SC2274: Command name starts with ===. Intended as a commented border?

SC2275: Command name starts with =. Bad line break?

SC2276: This is interpreted as a command name containing =. Bad assignment or comparison?

SC2277: Use BASH_ARGV0 to assign to $0 in bash (or use [ ] to compare).

SC2278: $0 can't be assigned in Ksh (but it does reflect the current function).

SC2279: $0 can't be assigned in Dash. This becomes a command name.

SC2280: $0 can't be assigned this way, and there is no portable alternative.

SC2281: Don't use $/${} on the left side of assignments.

SC2282: Variable names can't start with numbers, so this is interpreted as a command.

SC2283: Use [ ] to compare values, or remove spaces around = to assign (or quote '=' if literal).

SC2284: Use [ x = y ] to compare values (or quote '==' if literal).

SC2285: Remove spaces around += to assign (or quote '+=' if literal).

SC2286: This empty string is interpreted as a command name. Double check syntax (or use 'true' as a no-op).

SC2287: This is interpreted as a command name ending with '/'. Double check syntax.

SC2288: This is interpreted as a command name ending with apostrophe. Double check syntax.

SC2289: This is interpreted as a command name containing a linefeed. Double check syntax.

SC2290: Remove spaces around = to assign.

SC2291: Quote repeated spaces to avoid them collapsing into one.

SC2292: Prefer [[ ]] over [ ] for tests in Bash/Ksh.

SC2293: When eval'ing @Q-quoted words, use * rather than @ as the index.

SC2294: eval negates the benefit of arrays. Drop eval to preserve whitespace/symbols (or eval as string).

SC2295: Expansions inside ${..} need to be quoted separately, otherwise they will match as a pattern.

SC2296: Parameter expansions can't start with {. Double check syntax.

SC2297: Double quotes must be outside ${}: ${"invalid"} vs "${valid}".

SC2298: ${$x} is invalid. For expansion, use ${x}. For indirection, use arrays, ${!x} or (for sh) eval.

SC2299: Parameter expansions can't be nested. Use temporary variables.

SC2300: Parameter expansion can't be applied to command substitutions. Use temporary variables.

SC2301: Parameter expansion starts with unexpected quotes. Double check syntax.

SC2302: This loops over values. To loop over keys, use "${!array[@]}".

SC2303: i is an array value, not a key. Use directly or loop over keys instead.

SC2304: * must be escaped to multiply: \*. Modern $((x * y)) avoids this issue.

SC2305: Quote regex argument to expr to avoid it expanding as a glob.

SC2306: Escape glob characters in arguments to expr to avoid pathname expansion.

SC2307: 'expr' expects 3+ arguments but sees 1. Make sure each operator/operand is a separate argument, and escape <>&|.

SC2308: expr length has unspecified results. Prefer ${#var}.

SC2309: -eq treats this as a variable. Use = to compare as string (or expand explicitly with $var)

SC2310: This function is invoked in an 'if' condition so set -e will be disabled. Invoke separately if failures should cause the script to exit.

SC2311: Bash implicitly disabled set -e for this function invocation because it's inside a command substitution. Add set -e; before it or enable inherit_errexit.

SC2312: Consider invoking this command separately to avoid masking its return value (or use '|| true' to ignore).

SC2313: Quote array indices to avoid them expanding as globs.

SC2314: In bats, ! does not cause a test failure.

SC2315: In bats, ! does not cause a test failure. Fold the ! into the conditional!

SC2316: This applies local to the variable named readonly, which is probably not what you want. Use a separate command or the appropriate declare options instead.

SC2317: Command appears to be unreachable. Check usage (or ignore if invoked indirectly).

SC2318: This assignment is used again in this declare, but won't have taken effect. Use two declares.

SC2319: This $? refers to a condition, not a command. Assign to a variable to avoid it being overwritten.

SC2320: This $? refers to echo/printf, not a previous command. Assign to variable to avoid it being overwritten.

SC2321: Array indices are already arithmetic contexts. Prefer removing the $(( and )).

SC2322: In arithmetic contexts, ((x)) is the same as (x). Prefer only one layer of parentheses.

SC2323: a[(x)] is the same as a[x]. Prefer not wrapping in additional parentheses.

SC3001: In POSIX sh, process substitution is undefined.

SC3002: In POSIX sh, extglob is undefined.

SC3003: In POSIX sh, $'..' is undefined.

SC3004: In POSIX sh, $".." is undefined

SC3005: In POSIX sh, arithmetic for loops are undefined.

SC3006: In POSIX sh, standalone ((..)) is undefined.

SC3007: In POSIX sh, $[..] in place of $((..)) is undefined.

SC3008: In POSIX sh, select loops are undefined.

SC3009: In POSIX sh, brace expansion is undefined.

SC3010: In POSIX sh, [[ ]] is undefined.

SC3011: In POSIX sh, here-strings are undefined.

SC3012: In POSIX sh, lexicographical \< is undefined.

SC3013: In POSIX sh, -nt is undefined.

SC3014: In POSIX sh, == in place of = is undefined.

SC3015: In POSIX sh, =~ regex matching is undefined.

SC3016: In POSIX sh, unary -v (in place of [ -n "${var+x}" ]) is undefined.

SC3017: In POSIX sh, unary -a in place of -e is undefined.

SC3018: In POSIX sh, ++ is undefined.

SC3019: In POSIX sh, exponentials are undefined.

SC3020: In POSIX sh, &> is undefined.

SC3021: In POSIX sh, >& filename (as opposed to >& fd) is undefined.

SC3022: In POSIX sh, named file descriptors is undefined.

SC3023: In POSIX sh, FDs outside of 0-9 are undefined.

SC3024: In POSIX sh, += is undefined.

SC3025: In POSIX sh, /dev/{tcp,udp} is undefined.

SC3026: In POSIX sh, ^ in place of ! in glob bracket expressions is undefined.

SC3028: In POSIX sh, VARIABLE is undefined.

SC3029: In POSIX sh, |& in place of 2>&1 | is undefined.

SC3030: In POSIX sh, arrays are undefined.

SC3031: In POSIX sh, redirecting from/to globs is undefined.

SC3032: In POSIX sh, coproc is undefined.

SC3033: In POSIX sh, naming functions outside [a-zA-Z_][a-zA-Z0-9_]* is undefined.

SC3034: In POSIX sh, $(<file) is undefined.

SC3035: In POSIX sh, `<file` is undefined.

SC3036: In Dash, echo flags besides -n are not supported.

SC3037: In POSIX sh, echo flags are undefined.

SC3038: In POSIX sh, exec flags are undefined.

SC3039: In POSIX sh, let is undefined.

SC3040: In POSIX sh, set option *[name]* is undefined.

SC3041: In POSIX sh, set flag -E is undefined

SC3042: In POSIX sh, set flag --default is undefined

SC3043: In POSIX sh, local is undefined.

SC3044: In POSIX sh, declare is undefined.

SC3045: In POSIX sh, some-command-with-flag is undefined.

SC3046: In POSIX sh, source in place of . is undefined.

SC3047: In POSIX sh, trapping ERR is undefined.

SC3048: In POSIX sh, prefixing signal names with 'SIG' is undefined.

SC3049: In POSIX sh, using lower/mixed case for signal names is undefined.

SC3050: In POSIX sh, printf %q is undefined.

SC3051: In POSIX sh, source in place of . is undefined

SC3052: In POSIX sh, arithmetic base conversion is undefined

SC3053: In POSIX sh, indirect expansion is undefined.

SC3054: In POSIX sh, array references are undefined.

SC3055: In POSIX sh, array key expansion is undefined.

SC3056: In POSIX sh, name matching prefixes are undefined.

SC3057: In POSIX sh, string indexing is undefined.

SC3059: Case modification is not supported in dash and undefined in POSIX sh.

SC3060: In POSIX sh, string replacement is undefined.