AWS CloudFormation Linter

`for` loop used on `find` outputSH-2044 Opening and closing brackets do not matchSH-1033 Missing `fi` statement hereSH-1047 Missing `}`SH-1056 Missing `done` statementSH-1061 Missing `then` statementSH-1050 Semicolon detected after `else`SH-1053 `[ .. ]` is not a part of shell syntaxSH-1014 No `fi` found for the `if` statementSH-1046 Wrong way of declaring parametersSH-1065 Missing `EOF` tokenSH-1044 Unescaped `&` will end the command hereSH-1132 Consider using `elif` instead of `if`SH-1075 File has UTF-8 BOMSH-1082 Unexpected line-startSH-1133 Terminator used after here documentSH-1121 Avoid using literal tilde in PATHSH-2147 Empty `then` clause detectedSH-1048 Missing whitespaceSH-1020 Semicolon detected after `then`SH-1051 Missing space after `{`SH-1054 Found 'eof' further down, but not on a separate lineSH-1041 Non-alphanumeric names may have been skippedSH-2038 Found a comment after here-doc tokenSH-1120 Consider using command substitution instead of `'...'`SH-2041 Avoid use of `ls | grep`SH-2010 Consider using command substitution to assign the output of a pipelineSH-2036 Missing space after `$(`SH-1102 Leading spaces detected befor shebangSH-1114 Missing command substitutionSH-2037 Iterating over a constant valueSH-2043 Consider using glob to iterate over `ls` outputSH-2045 Consider using a `( subshell )` to avoid having to `cd` backSH-2103 Functions must not return multiple valuesSH-2151 Array expansion in string arguments may have unexpected resultsSH-2145 Evaluation order of arguments to `find` might be different than expectedSH-2146 Use `-exec sh -c` to invoke a shell with `find`SH-2150 Syntax errorSH-1070 `(( ))` doesn't support decimalsSH-2079 Missing space after `<`SH-1038 `$` used on the left side of an assignmentSH-1066 Whitespace found after `=`SH-1007 Apostrophe terminates the single quoted stringSH-1011 Missing `then` for the `if` statementSH-1049 Unary test operator not followed by a valid shell wordSH-1019 Missing `do` statementSH-1058 Unescaped `$` used in a literal contextSH-1000 Consider using `find` instead of `ls` to better handle non-alphanumeric filenamesSH-2012 Lexicographical comparison operator used for numerical comparisonSH-2071 Escape `\<` to prevent it redirecting (or switch to `[[ .. ]]`)SH-2073 Mismatched keywordSH-1089 Invalid use of parenthesesSH-1088 C language style commentSH-1127 `-n` doesn't work with unquoted argumentsSH-2070 Unexpected character after terminating `]`SH-1136 Consider using `pgrep` instead of grepping `ps` outputSH-2009 Shell functions passed to an external commandSH-2033 Consider using `&&` instead of `-a` in `[[..]]`SH-2108 use of an invalid operatorSH-2122 Found word outside quotesSH-2026 Unknown unary operatorSH-2058 Keyword is not in lower caseSH-1081 Loop will run only once because there's no word splittingSH-2066 Double quote array expansions to avoid re-splitting elementsSH-2068 Unnecessary use of `$` / `${}` with arithmetic variableSH-2004 Shebang with more than one parameterSH-2096 Missing `$`SH-1116 shebang is not the first lineSH-1128 Quote 'EOF' to make here document expansions happen on the server side rather than on the clientSH-2087 Bash doesn't allow variables in brace range expansionsSH-2051 `[ .. ]` can't match globsSH-2081 Unexpected `==`SH-1097 Variable modified locally due to `pipe`SH-2030 Command substitutions will run *before* the enclosing command instead of within itSH-2014 String not closedSH-1078 `=~` is not allowed in `[ ]`SH-2074 `>` behaves like a redirection operator hereSH-2065 Unknown binary operatorSH-2057 Shell functions passed to `su`SH-2032 Missing newline between the end token and terminating `)`SH-1119 `||` is not supported inside `[ .. ]`SH-2109 `break` used outside of a loopSH-2105 Use `[ a ] && [ b ]` instead of `[ a && b ]`SH-2107 Invalid `-o` in `[[..]]`SH-2110 A system directory is being deletedSH-2114 Aliases can't use positional parametersSH-2142 Consider using a `for` loop instead of `-e`SH-2144 Variables must be defined before useSH-2154 Missing space before `#`SH-1099 Use double quote to prevent globbing and word splittingSH-2086 Unquoted HTML entity foundSH-1109 Unicode double quotes detectedSH-1015 Can't escape `(` or `)` inside `[[..]]`SH-1029 `eof` is not on a separate lineSH-1042 Single quote not escaped properlySH-1003 Braces are required for positionals over 9SH-1037 Unicode single quote usedSH-1016 Invalid or unescaped `(` foundSH-1036 Script uses carriage return ` `SH-1017 Function definition missing bodySH-1064 Unnecessary use of multiple line terminatorsSH-1045 Assigning to a dynamically created variableSH-1067 Missing space before `[`SH-1069 backslash / linefeed is a literal where it is usedSH-1004 Detected a literal where `tab`, `linefeed` or `cariage return` might be expectedSH-1012 Escape `(` and `)` or preferably combine `[..]` expressionsSH-1028 Remove indentation before end tokenSH-1039 Use `( .. )` to group conditionsSH-1026 Unicode non-breaking space foundSH-1018 Use tabs for indentationSH-1040 Detected spaces around `=` operatorSH-1068 Use semicolon or linefeed before `done`SH-1010 Missing whitespaceSH-1035 Whitespace detected between `#` and `!` in the `shebang`SH-1115 Deprecated `$[..]` usedSH-2007 Unicode quote detectedSH-1110 Missing `!` in shebangSH-1113 Executing output of a commandSH-2091 Unused variableSH-2034 Useless `cat`SH-2002 Consider escaping `$` to make it a literalSH-1135 Consider using `$HOME` instead of tilde `~` to expand in quotesSH-2088 Whitespace detected after the here-doc end tokenSH-1118 Consider using braces to expand arraysSH-1087 `tr` used to replace wordsSH-2020 Remove `exec` if script should continue after this commandSH-2093 Consider escaping special characters when using `eval`SH-1098 Consider using `$((..))` for arithmetic operationsSH-2100 Increase precision by replacing `a/b*c` with `a*c/b`SH-2017 Use `[:upper:]` to support accents and foreign alphabetsSH-2019 Missing space or linefeed between the function name and bodySH-1095 Missing space before `!`SH-1129 Consider reformattingSH-1079 `echo` doesn't read from stdinSH-2008 `echo` used to expand escape sequencesSH-2028 Trailing spaces after `\`SH-1101 Named class needs an outer `[]`SH-2101 Verify use of the pipeline operatorSH-2106 Consider using `func()`SH-2113 Brace expansions/globs used in an assignmentSH-2125 Use `=` for non-integer comparisonsSH-2130 Shell search path `PATH` is being overriddenSH-2123 Consider using `grep -q`SH-2143 `=~` used with a globSH-2049 Use spaces to separate array elementsSH-2054 Consider using `while read` to read linesSH-2013 Quote parameter to prevent glob expansionSH-2060 Quote the passed parameter to prevent the shell from interpreting itSH-2061 To redirect both `stdout` and `stderr`, `2>&1` must be last (or use `'{ cmd > file; } 2>&1'` to clarify)SH-2069 Possibly missing `$`SH-2078 Missing space around `=` operatorSH-1108 Unnecessary use of `echo`SH-2005 Remove backticks to avoid executing outputSH-2092 Glob used with `grep`SH-2063 Remove '$' or use '_=$((expr))' to avoid executing outputSH-2084 `sudo` doesn't affect redirectsSH-2024 Use `"$@"` to prevent whitespace problemsSH-2048 `{` `/` `}` is a literal hereSH-1083 Command swallows `stdin`SH-2095 Unicode dash detectedSH-1100 `$` used on the iterator name in for loopsSH-1086 Unsupported decimalsSH-2072 Missing space before `:`SH-1130 `A && B || C` is not equivalent to `if A then B else C`SH-2015 Missing `;` or `+` terminating `-exec`SH-2067 Use `$((..))` for arithmetic operationSH-2099 Consider using `find` for better handling non-alphanumeric filenamesSH-2011 Use of variable in `printf` format stringSH-2059 Unescaped enclosed quotesSH-2027 Numbers with a leading `0` are considered octalSH-2080 Use double quotes to expand expressionsSH-2016 Quote the RHS of the operator to prevent glob matchingSH-2053 Quoting RHS of `=~` will match literally rather than as a regexSH-2076 Use of legacy backtickSH-2006 Consider using `./` or `--` globSH-2035 Enclose escape sequences in `\[..\]` to prevent line wrapping issuesSH-2025 Consider using `${variable//search/replace}`SH-2001 `trap` code will expand during definitionSH-2064 Missing `#` in the shebang lineSH-1104 Use `#!` for shebangSH-1084 Comparison with literalSH-2050 Unescaped argument foundSH-2029 Text added after here-doc terminating tokenSH-1122 Use backtick for command expansionSH-1077 Variable modified in the subshellSH-2031 To expand via indirection, use name="foo$n"; echo "${!name}"SH-2082 Assignment visible only to the forked processSH-2097 Encountered use of `[]` around ranges in `tr`SH-2021 Missing spaces around the comparison operatorSH-2077 Quote `grep` patterns to stop shells from interpreting themSH-2062 Consider quoting command expansion to prevent word splittingSH-2046 Make sure not to read and write the same file in the same pipelineSH-2094 Use `[:lower:]` to support accents and foreign alphabetsSH-2018 Use `elif` to start another branchSH-1131 Referred argument is never passedSH-2120 Do not use `set` to assign a variableSH-2121 Ranges can only match single charactersSH-2102 Consider using `return`SH-2104 Use `"${var:?}"` to ensure this never expands to `/*`SH-2115 Unnecessary use of `echo`SH-2116 Use `su -c` or `sudo` to run command as another userSH-2117 An array is being assigned to a stringSH-2124 Consider escaping the expansionSH-2139 Unquoted literal string detected between two double quoted stringsSH-2140 Potentially misspelled variable name foundSH-2153 Avoid using `$` with numeric or string indicesSH-2149 Function returns something other than a number in the range of 0-255SH-2152 Escaping a non-special characterSH-1001 Outdated `expr` statementSH-2003 Literal quote/backslash detected in the argument stringSH-2089 Consider using single quotesSH-2141 Consider using `${#variable}`SH-2000 Consider grouping multiple command redirectsSH-2129 Consider using `grep -c`SH-2126

SH-2014

Command substitutions will run before the enclosing command instead of within itSH-2014

Critical

Bug Risk

Problematic code:

find . -name '*.tar' -exec tar xf {} -C "$(dirname {})" \;

Preferred code:

find . -name '*.tar' -exec sh -c 'tar xf "$1" -C "$(dirname "$1")"' _ {} \;

Bash evaluates any command substitutions before the command they feature in is executed. In the given example, the command is find. This means that $(dirname {}) will run before find runs, and not while find runs.

To run shell code for each file, you can write a tiny script and inline it with sh -c. Add _ as a dummy argument that becomes $0, and a filename argument that becomes $1 in the inlined script:

$ sh -c 'echo "$1 is in $(dirname "$1")"' _ "mydir/myfile"
mydir/myfile is in mydir

This command can be executed by find -exec, with {} as the filename argument. It executes a shell which interprets the inlined script once for each file. Note that the inlined script is single quoted, again to ensure that the expansion does not happen prematurely.

Exception:

If you don't care that it's only expanded once, like when dynamically selecting the executable to be used by all invocations, you can ignore this message.