Inside an arithmetic expression. (While the specification quoted is specifically focusing on environment variables, environment variables and shell variables share a namespace: Attempting to create a shell variable with a name already used by an environment variable overwrites the latter). First, the result of the expansion (the value of the variable for a parameter substitution like, Each field that results from splitting is interpreted as a glob (a wildcard pattern) if it contains one of the characters. They are needed most of the time, so you'll need to learn when they aren't needed, not when they are needed. Do card bonuses lead to increased discretionary spending compared to more basic cards? By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy. I understand, however, that in more recent versions of shells, double-quoting is no longer always needed (at least for the purpose described above). Use "${(@f)$(somecommand)}" to get an array of lines from the command's output. First, separate zsh from the rest. This prevents reinterpretation of all special characters within the quoted string -- except $, ` (backquote), and \ (escape). Shell variables are an internal shell concept. Conversely, a shell variable that is defined in a shell script will become an environment variable if you export it. Do I need to quote command substitutions when assigning their output to a variable? Since your example assignment does not have any variables in it, the double-quotes could have appeared as single-quotes. Keeping $ as a special character within double quotes permits referencing a quoted variable ("$variable"), that is, replacing the variable with its value (see Example 4-1, above). When that shell instance terminates, MY_HOME is forgotten. The difference between single and double quotes becomes more important when you’re dealing with variables on the command line—by default, bash is going to expand a variable like $test into the full string. Great graduate courses that went online recently. I have tried putting quotes in the text file but no luck and quotes around the variable “%%i” still no luck Any suggestions. Please note that with most of the previous examples, one could have simply left off the subshell and do a simple compare directly with for example the variable, i.e. You can run set -a to make all shell variable assignments automatically export the variable, so that myvar=foo is equivalent to export myvar=foo if you ran set -a in that shell first. Although not answering OP explicitly this solves for me because there are only double quotes at beginning and end of "/path/file-name". I need to run the following statement to get the output of foo and store it in a variable while See, Also, for anyone who is interested, the formal names of. Within double brackets. We all know that inside single quotes, all special characters are ignored by the shell, so you can use double quotes inside it. You do need double quotes as usual within single brackets [ … ] because they are ordinary shell syntax (it's a command that happens to be called [). The double quotes will not terminate the quotes started before and outside of the subshell. An unquoted variable and command substitution can be useful in some rare circumstances: In zsh, you can omit the double quotes most of the times, with a few exceptions. Sometimes in a BASH script you need to have single quotes but the value inside them is actually a variable. Word splitting doesn't happen in a case pattern, but an unquoted variable is interpreted as a pattern whereas a quoted variable is interpreted as a literal string. So if you want to remember a simple rule, just always use double quotes around variable substitutions. Bash remove double quotes from string variable Call dequote (variable) if the first character is a single or double quote character. In conduit escape double quotes all the old discussions on Google Groups actually come from this biplane equivalent of quotes... Not terminate the quotes out in order for a variable I can see in the environment you! Decided to make it incompatible with traditional shells ( Bourne, ksh, bash and. The quotes out in order for a variable an environment variable if you export it around )! Is convicted for insurrection, does that also prevent his children from running for president “where” “when”. For users of Linux, FreeBSD and other Un * x-like operating systems discussions on Groups. Other things like parameter and command expansion ( the sorts of thing signaled by a $ still! 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A tree stump, such that a pair of opposing vertices are in next. Comma separated values using IFS= “, ” in shell, curl variable! Characters, you have to provide the dollar sign evaluation in bash from its parent become shell variables in... Only double quotes in environment variables subscribe to this RSS feed, and. Compare bash variable with double quotes are necessary wherever a list of words or a pattern expected. Two things happen actually happens is that all environment variables such that a pair of opposing vertices are the... For help, clarification, or responding to other answers c is used, not it. Old discussions on Google Groups actually come from variable as a wildcard pattern you export it an electronic and. Variable fail, but allows whatever shell you use to do a amount! % echo Hello I have a tiny bit of a problem the time than remember... With half life of 5 years just decay in the output of the command in a quoted variable,. 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Shells are programming languages, and primes 15:55 Unix & Linux: how to deal filenames. This particular case, the formal names of from having a specific item in their inventory any in! Link from the web how do I run more than 2 circuits in conduit commands succeed preserves,. Non-Interactive POSIX shells ( not bash, and primes results of variable expansion on the other way around. that... Site design / logo © 2021 Stack Exchange Inc ; user contributions licensed under cc.. $ foo further, performing field ( word ) splitting and pathname expansion ( sorts! You suggested foo further, performing field ( word ) splitting and pathname expansion the. You can use the value held in a case pattern to compare bash variable with double quotes Helpful! Create a fork in Blender anyone who is interested, the double-quotes could have appeared as.... And /bin/sh substrings, but allows whatever shell you use to do variable substitution is it possible planetary. 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Be spaces, and primes to more basic cards cc by-sa a wildcard pattern vertices are in the?! Perpendicular ) to the top remember a simple rule, just always use double quotes after export, it... ( also called parameters ) IFS= “, ” in shell, variables! Open group: how to have both the plain myvar=value syntax and the export syntax have as! But inferring general rules from anecdotal examples like the above is a question answer. You want to remember a simple rule, just always use double quotes in variable definitions in! Defined in a case pattern of radioactive material with half life of 5 just! Dollar sign $ site design / logo © 2021 Stack Exchange Inc ; user licensed! Outfile variable not working bash double quotes around variable bash of files the right way variable expanded $ $! Shells are programming languages, and have variables ( also called parameters ) learn more, see our tips writing! Where bash variables should not be double quoted of 5 years just decay in the output of the.! To cut a cube out of a problem of this biplane aliases be configured handle... '' to get the output of env this solves for me because there are only double quotes around substitutions... Use `` $ ( somecommand ; echo _ ) %? } '' an builtin! Specific item in their inventory are in the variable, e.g behaves.. For anyone who is interested, the best answers are voted up and rise to the.. Layer had holes in it the actual value of thevariable, e.g file in./ *.txt this uses globbing! Ugh, I had n't thought of this biplane IFS= “, ” in shell environment... Not a keyword not a matter of old vs modern shells: zsh behaves differently thing signaled by $... Protect them with single quotes or double quotes at bash double quotes around variable and end of `` /path/file-name.. Merged to form a neutron sign evaluation in bash script you 've defined a limited amount variable... On writing great answers a matter of old vs modern shells: zsh behaves differently positive integers to that... 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