Check if a Bash array contains a value

Question

In Bash  what is the simplest way to test if an array contains a certain value

User · Answer

How to check if a Bash Array contains a value

False positive match

array=(a1 b1 c1 d1 ee)

[[ ${array[*]} =~ 'a' ]] && echo 'yes' || echo 'no'
# output:
yes

[[ ${array[*]} =~ 'a1' ]] && echo 'yes' || echo 'no'
# output:
yes

[[ ${array[*]} =~ 'e' ]] && echo 'yes' || echo 'no'
# output:
yes

[[ ${array[*]} =~ 'ee' ]] && echo 'yes' || echo 'no'
# output:
yes

Exact match

In order to look for an exact match, your regex pattern needs to add extra space before and after the value like (^|[[:space:]])"VALUE"($|[[:space:]])

# Exact match

array=(aa1 bc1 ac1 ed1 aee)

if [[ ${array[*]} =~ (^|[[:space:]])"a"($|[[:space:]]) ]]; then
    echo "Yes";
else
    echo "No";
fi
# output:
No

if [[ ${array[*]} =~ (^|[[:space:]])"ac1"($|[[:space:]]) ]]; then
    echo "Yes";
else
    echo "No";
fi
# output:
Yes

find="ac1"
if [[ ${array[*]} =~ (^|[[:space:]])"$find"($|[[:space:]]) ]]; then
    echo "Yes";
else
    echo "No";
fi
# output:
Yes

For more usage examples the source of examples are here

User · Answer

I generally write these kind of utilities to operate on the name of the variable  rather than the variable value  primarily because bash can t otherwise pass variables by reference   Here s a version that works with the name of the array   function array contains   array value          -n   1   amp  amp  -n   2                  echo  usage  array contains  lt array gt   lt value gt           echo  Returns 0 if array contains value  1 otherwise          return 2            eval  local values       1              local element     for element in    values       do              element       2      amp  amp  return 0     done     return 1     With this  the question example becomes   array contains A  one   amp  amp  echo  contains one    etc

User · Answer

A small addition to  ghostdog74 s answer about using case logic to check that array contains particular value   myarray  one two three  word two case    myarray      in     word        word        word   echo  found     esac   Or with extglob option turned on  you can do it like this   myarray  one two three  word two shopt -s extglob case    myarray      in          word          echo  found     esac   Also we can do it with if statement   myarray  one two three  word two if      printf     s       myarray                word          then echo  found   fi

User · Answer

Although there were several great and helpful answers here  I didn t find one that seemed to be the right combination of performant  cross-platform  and robust  so I wanted to share the solution I wrote for my code      bin bash    array contains   needle     haystack          Returns 0 if an item   1  is contained in an array           Developer note       The use of a delimiter here leaves something to be desired  The ideal      method seems to be to use  grep  with --line-regexp and --null-data  but      Mac BSD grep doesn t support --line-regexp  function array contains           Extract and remove the needle from         local needle   1      shift        Separates strings in the array for matching  Must be extremely-unlikely       to appear in the input array or the needle      local delimiter    - 8 -           Create a string with containing every  delimited  element in the array        and search it for the needle with grep in fixed-string mode      if printf    delimiter  s  delimiter                    grep --fixed-strings --quiet    delimiter   needle   delimiter    then         return 0     fi      return 1

User · Answer

given    array   something to search for   a string   test2000   elem  a string    then a simple check of    if c    x1E   amp  amp  p    c   elem    c    amp  amp          array        c     c       p     then   echo   elem exists in array  fi   where  c is element separator p is regex pattern    The reason for assigning p separately  rather than using the expression directly inside       is to maintain compatibility for bash 4

User · Answer

One-line solution printf   s n   quot   myarray     quot    grep -P   mypattern     Explanation The printf statement prints each element of the array on a separate line  The grep statement uses the special characters   and   to find a line that contains exactly the pattern given as mypattern  no more  no less    Usage To put this into an if     then statement  if printf   s n   quot   myarray     quot    grep -q -P   mypattern    then           fi  I added a -q flag to the grep expression so that it won t print matches  it will just treat the existence of a match as  quot true  quot

User · Answer

Using parameter expansion        parameter  word  If parameter is null or unset  nothing is   substituted  otherwise the expansion of word is substituted    declare -A myarray myarray hello   world   for i in hello goodbye 123 do   if     myarray  i          then     echo    myarray  i     myarray  i      else     printf  there is no  s n   i   fi done

User · Answer

Here is a small contribution    array  word  two words  words    search string  two    match   echo    array    0     grep -o  search string         -z  match     amp  amp  echo  found        Note  this way doesn t distinguish the case  two words  but this is not required in the question

User · Answer

My version of the regular expressions technique that s been suggested already   values  foo bar  requestedValue bar  requestedValue   requestedValue     space     requestedValue   requestedValue     space           values      X-       X-  requestedValue         echo  Unsupported value    What s happening here is that you re expanding the entire array of supported values into words and prepending a specific string   X-  in this case  to each of them  and doing the same to the requested value  If this one is indeed contained in the array  then the resulting string will at most match one of the resulting tokens  or none at all in the contrary  In the latter case the    operator triggers and you know you re dealing with an unsupported value  Prior to all of that the requested value is stripped of all leading and trailing whitespace through standard shell string manipulation   It s clean and elegant  I believe  though I m not too sure of how performant it may be if your array of supported values is particularly large

User · Answer

Here s a compilation of several possible implementations  complete with integrated verification and simple benchmarking     usr bin env bash    Check if array contains item   1  item   2  array name  function in array 1         local needle  quot  1 quot  item     local -n arrref  quot  2 quot      for item in  quot   arrref     quot   do             quot   item  quot      quot   needle  quot      amp  amp  return 0     done     return 1      Check if array contains item   1  item   2  array name  function in array 2         local needle  quot  1 quot  arrref  quot  2    quot  item     for item in  quot    arrref  quot   do             quot   item  quot      quot   needle  quot      amp  amp  return 0     done     return 1      Check if array contains item   1  item   2  array name  function in array 3         local needle  quot  1 quot  i     local -n arrref  quot  2 quot      for   i 0  i  lt     arrref      i      do             quot   arrref i   quot      quot   needle  quot      amp  amp  return 0     done     return 1      Check if array contains item   1  item   2   n  array items  function in array 4         local needle  quot  1 quot  item     shift     for item  do             quot   item  quot      quot   needle  quot      amp  amp  return 0     done     return 1      Check if array contains item   1  item   2   n  array items  function in array 5         local needle  quot  1 quot  item     for item in  quot     2  quot   do             quot   item  quot      quot   needle  quot      amp  amp  return 0     done     return 1      Check if array contains item   1  item   2  array name  function in array 6         local needle  quot  1 quot  arrref  quot  2    quot  array i     array   quot    arrref  quot       for   i 0  i  lt     array      i      do             quot   array i   quot      quot   needle  quot      amp  amp  return 0     done     return 1      Check if array contains item   1  item   2   n  array items  function in array 7         local needle  quot  1 quot  array   quot     2  quot   item     for item in  quot   array     quot   do             quot   item  quot      quot   needle  quot      amp  amp  return 0     done     return 1      Check if array contains item   1  item   2   n  array items  function in array 8         local needle  quot  1 quot      shift     while        gt  0     do             quot  1 quot      quot   needle  quot      amp  amp  return 0         shift     done     return 1      ------------------------------------------------------------------------------     Generate map for array   1  name of source array   2  name of target array    NOTE  target array must be pre-declared by caller using  declare -A  lt name gt   function generate array map         local -n srcarr  quot  1 quot  dstmap  quot  2 quot      local i key     dstmap        for i in  quot    srcarr     quot   do         key  quot   srcarr i   quot             -z   dstmap  quot   key  quot   set      amp  amp  dstmap  quot   key  quot     i     dstmap  quot   key  quot       i      done      Check if array contains item   1  item   2  name of array map  function in array 9         local needle  quot  1 quot      local -n mapref  quot  2 quot         -n  quot   mapref  quot   needle  quot   set  quot      amp  amp  return 0    return 1      ------------------------------------------------------------------------------     Test in array function   1  function name   2  function description   3  test array size  function test         local tname  quot  1 quot  tdesc  quot  2 quot  tn  3 ti 0 tj 0 ta    tct 0 tepapre  quot  quot  tepapost  quot  quot  tepadiff        local -A tam         echo -e  quot  e 1m  tname     tdesc    e 0m quot         Generate list of currently defined variables     tepapre  quot   compgen -v  quot         Fill array with random items     for   ti 0  ti  lt    tn   ti      do         ta    quot   RANDOM    RANDOM    RANDOM    RANDOM  quot       done        Determine function call type  pass array items  pass array name  pass array map      case  quot   tname  quot  in          quot in array 1 quot   quot in array 2 quot   quot in array 3 quot   quot in array 6 quot   tct 0              quot in array 4 quot   quot in array 5 quot   quot in array 7 quot   quot in array 8 quot   tct 1              quot in array 9 quot   generate array map ta tam  tct 2                echo  quot Unknown in array function    tname    aborting quot   return 1         esac        Verify in array function is working as expected by picking a few random       items and checking     echo -e  quot  e 1mVerification    e 0m quot      for   ti 0  ti  lt  10  ti      do         tj       RANDOM       ta                echo -n  quot Item   tj     ta tj      quot          if      tct     0     then              quot   tname  quot   quot   ta tj   quot  ta  amp  amp  echo -en  quot  e 1 32mok e 0m quot     echo -en  quot  e 1 31mnok e 0m quot              echo -n  quot   quot               quot   tname  quot   quot   ta tj   x quot  ta  amp  amp  echo -en  quot  e 1 31mnok e 0m quot     echo -en  quot  e 1 32mok e 0m quot          elif      tct     1     then              quot   tname  quot   quot   ta tj   quot   quot   ta     quot   amp  amp  echo -en  quot  e 1 32mok e 0m quot     echo -en  quot  e 1 31mnok e 0m quot              echo -n  quot   quot               quot   tname  quot   quot   ta tj   x quot   quot   ta     quot   amp  amp  echo -en  quot  e 1 31mnok e 0m quot     echo -en  quot  e 1 32mok e 0m quot          elif      tct     2     then              quot   tname  quot   quot   ta tj   quot  tam  amp  amp  echo -en  quot  e 1 32mok e 0m quot     echo -en  quot  e 1 31mnok e 0m quot              echo -n  quot   quot               quot   tname  quot   quot   ta tj   x quot  tam  amp  amp  echo -en  quot  e 1 31mnok e 0m quot     echo -en  quot  e 1 32mok e 0m quot          fi         echo     done        Benchmark in array function     echo -en  quot  e 1mBenchmark    e 0m quot      time for   ti 0  ti  lt     ta      ti      do         if      tct     0     then              quot   tname  quot   quot   ta ti   quot  ta         elif      tct     1     then              quot   tname  quot   quot   ta ti   quot   quot   ta     quot          elif      tct     2     then              quot   tname  quot   quot   ta ti   quot  tam         fi     done        Generate list of currently defined variables  compare to previously       generated list to determine possible environment pollution     echo -e  quot  e 1mEPA test    e 0m quot      tepapost  quot   compgen -v  quot      readarray -t tepadiff  lt   lt  echo -e  quot   tepapre  n  tepapost  quot    sort   uniq -u      if       tepadiff        0     then         echo -e  quot  e 1 32mclean e 0m quot      else         echo -e  quot  e 1 31mpolluted  e 0m   tepadiff     quot      fi      echo      ------------------------------------------------------------------------------     Test in array functions n 5000 echo   test in array 1  quot pass array name  nameref reference  for-each-loop over array items quot    n      test in array 2  quot pass array name  indirect reference  for-each-loop over array items quot    n      test in array 3  quot pass array name  nameref reference  c-style for-loop over array items by index quot    n      test in array 4  quot pass array items  for-each-loop over arguments quot    n      test in array 5  quot pass array items  for-each-loop over arguments as array quot    n      test in array 6  quot pass array name  indirect reference   array copy  c-style for-loop over array items by index quot    n      test in array 7  quot pass array items  copy array from arguments as array  for-each-loop over array items quot    n      test in array 8  quot pass array items  while-loop  shift over arguments quot    n      test in array 9  quot pre-generated array map  pass array map name  direct test without loop quot    n     Results  in array 1  pass array name  nameref reference  for-each-loop over array items   Verification    Item 862  19528 10140 12669 17820   ok ok Item 2250  27262 30442 9295 24867   ok ok Item 4794  3857 17404 31925 27993   ok ok Item 2532  14553 12282 26511 32657   ok ok Item 1911  21715 8066 15277 27126   ok ok Item 4289  3081 10265 16686 19121   ok ok Item 4837  32220 1758 304 7871   ok ok Item 901  20652 23880 20634 14286   ok ok Item 2488  14578 8625 30251 9343   ok ok Item 4165  4514 25064 29301 7400   ok ok Benchmark    real    1m11 796s user    1m11 262s sys     0m0 473s EPA test    clean  in array 2  pass array name  indirect reference  for-each-loop over array items   Verification    Item 2933  17482 25789 27710 2096   ok ok Item 3584  876 14586 20885 8567   ok ok Item 872  176 19749 27265 18038   ok ok Item 595  6597 31710 13266 8813   ok ok Item 748  569 9200 28914 11297   ok ok Item 3791  26477 13218 30172 31532   ok ok Item 2900  3059 8457 4879 16634   ok ok Item 676  23511 686 589 7265   ok ok Item 2248  31351 7961 17946 24782   ok ok Item 511  8484 23162 11050 426   ok ok Benchmark    real    1m11 524s user    1m11 086s sys     0m0 437s EPA test    clean  in array 3  pass array name  nameref reference  c-style for-loop over array items by index   Verification    Item 1589  747 10250 20133 29230   ok ok Item 488  12827 18892 31996 1977   ok ok Item 801  19439 25243 24485 24435   ok ok Item 2588  17193 18893 21610 9302   ok ok Item 4436  7100 655 8847 3068   ok ok Item 2620  19444 6457 28835 24717   ok ok Item 4398  4420 16336 612 4255   ok ok Item 2430  32397 2402 12631 29774   ok ok Item 3419  906 5361 32752 7698   ok ok Item 356  9776 16485 20838 13330   ok ok Benchmark    real    1m17 037s user    1m17 019s sys     0m0 005s EPA test    clean  in array 4  pass array items  for-each-loop over arguments   Verification    Item 1388  7932 15114 4025 15625   ok ok Item 3900  23863 25328 5632 2752   ok ok Item 2678  31296 4216 17485 8874   ok ok Item 1893  16952 29047 29104 23384   ok ok Item 1616  19543 5999 4485 22929   ok ok Item 93  14456 2806 12829 19552   ok ok Item 265  30961 19733 11863 3101   ok ok Item 4615  10431 9566 25767 13518   ok ok Item 576  11726 15104 11116 74   ok ok Item 3829  19371 25026 6252 29478   ok ok Benchmark    real    1m30 912s user    1m30 740s sys     0m0 011s EPA test    clean  in array 5  pass array items  for-each-loop over arguments as array   Verification    Item 1012  29213 31971 21483 30225   ok ok Item 2802  4079 5423 29240 29619   ok ok Item 473  6968 798 23936 6852   ok ok Item 2183  20734 4521 30800 2126   ok ok Item 3059  14952 9918 15695 19309   ok ok Item 1424  25784 28380 14555 21893   ok ok Item 1087  16345 19823 26210 20083   ok ok Item 257  28890 5198 7251 3866   ok ok Item 3986  29035 19288 12107 3857   ok ok Item 2509  9219 32484 12842 27472   ok ok Benchmark    real    1m53 485s user    1m53 404s sys     0m0 077s EPA test    clean  in array 6  pass array name  indirect reference   array copy  c-style for-loop over array items by index   Verification    Item 4691  25498 10521 20673 14948   ok ok Item 263  25265 29824 3876 14088   ok ok Item 2550  2416 14274 12594 29740   ok ok Item 2269  2769 11436 3622 28273   ok ok Item 3246  23730 25956 3514 17626   ok ok Item 1059  10776 12514 27222 15640   ok ok Item 53  23813 13365 16022 4092   ok ok Item 1503  6593 23540 10256 17818   ok ok Item 2452  12600 27404 30960 26759   ok ok Item 2526  21190 32512 23651 7865   ok ok Benchmark    real    1m54 793s user    1m54 326s sys     0m0 457s EPA test    clean  in array 7  pass array items  copy array from arguments as array  for-each-loop over array items   Verification    Item 2212  12127 12828 27570 7051   ok ok Item 1393  19552 26263 1067 23332   ok ok Item 506  18818 8253 14924 30710   ok ok Item 789  9803 1886 17584 32686   ok ok Item 1795  19788 27842 28044 3436   ok ok Item 376  4372 16953 17280 4031   ok ok Item 4846  19130 6261 21959 6869   ok ok Item 2064  2357 32221 22682 5814   ok ok Item 4866  10928 10632 19175 14984   ok ok Item 1294  8499 11885 5900 6765   ok ok Benchmark    real    2m35 012s user    2m33 578s sys     0m1 433s EPA test    clean  in array 8  pass array items  while-loop  shift over arguments   Verification    Item 134  1418 24798 20169 9501   ok ok Item 3986  12160 12021 29794 29236   ok ok Item 1607  26633 14260 18227 898   ok ok Item 2688  18387 6285 2385 18432   ok ok Item 603  1421 306 6102 28735   ok ok Item 625  4530 19718 30900 1938   ok ok Item 4033  9968 24093 25080 8179   ok ok Item 310  6867 9884 31231 29173   ok ok Item 661  3794 4745 26066 22691   ok ok Item 4129  3039 31766 6714 4921   ok ok Benchmark    real    5m51 097s user    5m50 566s sys     0m0 495s EPA test    clean  in array 9  pre-generated array map  pass array map name  direct test without loop   Verification    Item 3696  661 6048 13881 26901   ok ok Item 815  29729 13733 3935 20697   ok ok Item 1076  9220 3405 18448 7240   ok ok Item 595  8912 2886 13678 24066   ok ok Item 2803  13534 23891 5344 652   ok ok Item 1810  12528 32150 7050 1254   ok ok Item 4055  21840 7436 1350 15443   ok ok Item 2416  19550 28434 17110 31203   ok ok Item 1630  21054 2819 7527 953   ok ok Item 1044  30152 22211 22226 6950   ok ok Benchmark    real    0m0 128s user    0m0 128s sys     0m0 000s EPA test    clean

User · Answer

This approach has the advantage of not needing to loop over all the elements  at least not explicitly    But since array to string internal   in array c still loops over array elements and concatenates them into a string  it s probably not more efficient than the looping solutions proposed  but it s more readable   if        array              value        then       whatever you want to do when array contains value fi  if          array              value        then       whatever you want to do when array doesn t contain value fi   Note that in cases where the value you are searching for is one of the words in an array element with spaces  it will give false positives   For example  array   Jack Brown   value  Jack    The regex will see  Jack  as being in the array even though it isn t   So you ll have to change IFS and the separator characters on your regex if you want still to use this solution  like this  IFS    t  array   Jack Brown tJack Smith   unset IFS value  Jack   if      t  array     t       t  value  t      then     echo  true  else     echo  false  fi   This will print  false    Obviously this can also be used as a test statement  allowing it to be expressed as a one-liner         array              value        amp  amp  echo  true     echo  false

User · Answer

The answer with most votes is very concise and clean  but it can have false positives when a space is part of one of the array elements  This can be overcome when changing IFS and using  quot   array     quot  instead of  quot   array     quot   The method is identical  but it looks less clean  By using  quot   array     quot   we print all elements of  array  separated by the first character in IFS  So by choosing a correct IFS  you can overcome this particular issue  In this particular case  we decide to set IFS to an uncommon character    001  which stands for Start of Heading  SOH    array   quot foo bar quot   quot baz quot   quot qux quot     IFS    001        quot  IFS  array     IFS quot      quot   IFS foo  IFS  quot      amp  amp  echo yes    echo no no       quot  IFS  array     IFS quot      quot   IFS foo bar  IFS  quot      amp  amp  echo yes    echo no yes   unset IFS  This resolves most issues false positives  but requires a good choice of IFS  note  If IFS was set before  it is best to save it and reset it instead of using unset IFS  related   Accessing bash command line args    vs

User · Answer

for i in    array      do     if     i  -eq   yourValue      then         echo  Found      fi done   For strings   for i in    array      do     if     i       yourValue      then         echo  Found      fi done

User · Answer

If you want to do a quick and dirty test to see if it s worth iterating over the whole array to get a precise match  Bash can treat arrays like scalars  Test for a match in the scalar  if none then skipping the loop saves time  Obviously you can get false positives   array  word  two words  words  if      array        words    then     echo  Checking      for element in    array          do         if     element     words             then             echo  Match          fi     done fi   This will output  Checking  and  Match   With array  word  two words  something  it will only output  Checking   With array  word  two widgets  something  there will be no output

User · Answer

Combining a few of the ideas presented here you can make an elegant if statment without loops that does exact word matches  find  quot myword quot  array  value1 value2 myword  if      -z   printf   s n   quot   array     quot    grep -w  find      then   echo  quot Array contains myword quot   fi  This will not trigger on word or val  only whole word matches  It will break if each array value contains multiple words

User · Answer

Here is my take on this problem  Here is the short version   function arrayContains             local haystack    1          local needle   2          printf   s n    haystack       grep -q    needle       And the long version  which I think is much easier on the eyes     With added utility function  function arrayToLines             local array    1          printf   s n    array        function arrayContains             local haystack    1          local needle   2          arrayToLines haystack      grep -q    needle       Examples   test arr   hello   world   arrayContains test arr    hello    True arrayContains test arr    world    True arrayContains test arr     hello world     False arrayContains test arr     hell     False arrayContains test arr          False

User · Answer

I typically just use   inarray   echo   haystack       grep -o  needle    wc -w    non zero value indicates a match was found

User · Answer

The following code checks if a given value is in the array and returns its zero-based offset   A   one   two   three four   VALUE  two   if       declare -p A           0-9         VALUE       then   echo  Found  VALUE at offset   BASH REMATCH 1    else   echo  Couldn t find  VALUE  fi   The match is done on the complete values  therefore setting VALUE  three  would not match

User · Answer

Borrowing from Dennis Williamson s answer  the following solution combines arrays  shell-safe quoting  and regular expressions to avoid the need for  iterating over loops  using pipes or other sub-processes  or using non-bash utilities   declare -a array   hello  stack  one  two words  words last  printf -v array str --     q     array       if       array str          words      then    echo  Matches  else    echo  Doesn t match  fi   The above code works by using Bash regular expressions to match against a stringified version of the array contents   There are six important steps to ensure that the regular expression match can t be fooled by clever combinations of values within the array    Construct the comparison string by using Bash s built-in printf shell-quoting   q   Shell-quoting will ensure that special characters become  shell-safe  by being escaped with backslash    Choose a special character to serve as a value delimiter   The delimiter HAS to be one of the special characters that will become escaped when using  q  that s the only way to guarantee that values within the array can t be constructed in clever ways to fool the regular expression match   I choose comma   because that character is the safest when eval d or misused in an otherwise unexpected way  Combine all array elements into a single string  using two instances of the special character to serve as delimiter   Using comma as an example  I used    q as the argument to printf   This is important because two instances of the special character can only appear next to each other when they appear as the delimiter  all other instances of the special character will be escaped  Append two trailing instances of the delimiter to the string  to allow matches against the last element of the array   Thus  instead of comparing against   array str   compare against   array str     If the target string you re searching for is supplied by a user variable  you must escape all instances of the special character with a backslash   Otherwise  the regular expression match becomes vulnerable to being fooled by cleverly-crafted array elements  Perform a Bash regular expression match against the string

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I had the case that I had to check if an ID was contained in a list of IDs generated by another script   command  For me worked the following     the ID I was looking for ID 1    somehow generated list of IDs LIST     lt some script that generates lines with IDs gt      list is curiously concatenated with a single space character LIST    LIST      grep for exact match  boundaries are marked as space   would therefore not reliably work for values containing a space   return the count with  -c  ISIN   echo  LIST   grep -F    ID   -c     do your check  e  g  0 for nothing found  everything greater than 0 means found  if   ISIN -eq 0    then     echo  not found  fi   etc    You could also shorten   compact it like this   if     echo       lt script call gt        grep -F    ID   -c  -eq 0    then     echo  not found  fi   In my case  I was running jq to filter some JSON for a list of IDs and had to later check if my ID was in this list and this worked the best for me  It will not work for manually created arrays of the type LIST   1   2   4   but for with newline separated script output     PS   could not comment an answer because I m relatively new

User · Answer

containsElement      for e in      2    do      e      1      amp  amp  return 0  done  return 1      Now handles empty arrays correctly

User · Answer

This is working for me     traditional system call return values-- used in an  if   this will be true when returning 0  Very Odd  contains            odd syntax here for passing array parameters  http   stackoverflow com questions 8082947 how-to-pass-an-array-to-a-bash-function     local list  1        local elem  2        echo  list     list        echo  elem   elem      for i in     list       do           echo  Checking to see if    i   is the same as     elem           if     i        elem       then               echo   i   was the same as     elem               return 0         fi     done        echo  Could not find element      return 1     Example call   arr   abc   xyz   123   if contains arr  abcx   then     echo  Yes  else     echo  No  fi

User · Answer

This could be worth investigating if you don t want to iterate      bin bash myarray   one   two   three    wanted  two  if  echo   myarray      wanted   WAS FOUND     grep -q  WAS FOUND      then  echo  Value was found  fi exit   Snippet adapted from  http   www thegeekstuff com 2010 06 bash-array-tutorial  I think it is pretty clever   EDIT  You could probably just do   if  echo   myarray       grep -q   wanted     then echo  Value was found  fi   But the latter only works if the array contains unique values  Looking for 1 in  143  will give false positive  methinks

User · Answer

Another one liner without a function    for e in    array       do      e      searched item      amp  amp  exit 0  done   amp  amp  echo  found     echo  not found    Thanks  Qwerty for the heads up regarding spaces   corresponding function   find in array       local word  1   shift   for e in       do      e       word      amp  amp  return 0  done   return 1     example   some words   these are some words   find in array word    some words         echo  expected missing  since words    word

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A little late  but you could use this      bin bash   isPicture sh  FILE  1 FNAME   basename   FILE     Filename  without directory EXT    FNAME         Extension  FORMATS  jpeg JPEG jpg JPG png PNG gif GIF svg SVG tiff TIFF   NOEXT     FORMATS     EXT      Formats without the extension of the input file    If it is a valid extension  then it should be removed from   NOEXT     making the lengths inequal  if        NOEXT           FORMATS        then     echo  The extension    EXT   is not a valid image extension       exit fi

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I came up with this one  which turns out to work only in zsh  but I think the general approach is nice   arr    hello world   find me   what     if       arr      find me          arr          then     echo  found   else     echo  not found   fi   You take out your pattern from each element only if it starts   arr     pattern   or ends   arr     pattern   with it  These two substitutions work in bash  but both at the same time   arr      pattern   only works in zsh   If the modified array is equal to the original  then it doesn t contain the element   Edit   This one works in bash    function contains              local arr      2           local el  1         local marr    arr      el                   arr             marr                 After the substitution it compares the length of both arrays  Obly if the array contains the element the substitution will completely delete it  and the count will differ

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a  b c d   if printf   s 0     a        grep -Fqxz c then   echo  array    a    contains value    c     fi   If you prefer you can use equivalent long options   --fixed-strings --quiet --line-regexp --null-data

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myarray  one two three    case    myarray      in    two    echo  found     esac found

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One-line check without  grep  and loops  if   dlm    x1F    IFS   dlm         dlm  array     dlm        dlm  item  dlm          then   echo  array contains   item   else   echo  array does not contain   item   fi   This approach uses neither external utilities like grep nor loops   What happens here  is    we use a wildcard substring matcher to find our item in the array that is concatenated into a string  we cut off possible false positives by enclosing our search item between a pair of delimiters  we use a non-printable character as delimiter  to be on the safe side  we achieve our delimiter being used for array concatenation too by temporary replacement of the IFS variable value  we make this IFS value replacement temporary by evaluating our conditional expression in a sub-shell  inside a pair of parentheses

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Using grep and printf  Format each array member on a new line  then grep the lines     if printf   s n     array        grep -x -q  search string   then echo true  else echo false  fi   example     array   word    two words     if printf   s n     array        grep -x -q  two words   then echo true  else echo false  fi true   Note that this has no problems with delimeters and spaces

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A combination of answers by Beorn Harris and loentar gives one more interesting one-liner test   delim    x1F    define a control code to be used as more or less reliable delimiter if       delim   array      delim         delim a string to test  delim       then     echo  contains  a string to test   fi   This one does not use extra functions  does not make replacements for testing and adds extra protection against occasional false matches using a control code as a delimiter     UPD  Thanks to  ChrisCogdon note  this incorrect code was re-written and published as https   stackoverflow com a 58527681 972463

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After having answered  I read another answer that I particularly liked  but it was flawed and downvoted  I got inspired and here are two new approaches I see viable   array   word   two words     let s look for  two words    using grep and printf    printf   s n     array        grep -x -q  two words    amp  amp   lt run your if found command here gt    using for    for e in    array       do      e      two words      amp  amp  exit 0  done  exit 1   amp  amp   lt run your if found command here gt    For not found results add     lt run your if notfound command here gt

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If you need performance  you don t want to loop over your whole array every time you search   In this case  you can create an associative array  hash table  or dictionary  that represents an index of that array  I e  it maps each array element into its index in the array     make index        local index name  1   shift   local -a value array          local i     -A means associative array  -g means create a global variable    declare -g -A   index name    for i in     value array       do     eval   index name     value array  i      i   done     Then you can use it like this   myarray   a a   b b   c c   make index myarray index    myarray        And test membership like so   member  b b    the     echo NOT FOUND  below is needed if you re using  set -e  test    myarray index  member     amp  amp  echo FOUND    echo NOT FOUND   Or also   if      myarray index  member       then    echo FOUND fi   Notice that this solution does the right thing even if the there are spaces in the tested value or in the array values   As a bonus  you also get the index of the value within the array with   echo   lt  lt    myarray index  member    gt  gt  is the index of  member

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The OP added the following answer themselves  with the commentary   With help from the answers and the comments  after some testing  I came up with this   function contains         local n        local value    n      for   i 1 i  lt     i               if    quot    i  quot      quot   value  quot     then             echo  quot y quot              return 0         fi           echo  quot n quot      return 1    A   quot one quot   quot two quot   quot three four quot   if     contains  quot   A     quot   quot one quot       quot y quot     then     echo  quot contains one quot  fi if     contains  quot   A     quot   quot three quot       quot y quot     then     echo  quot contains three quot  fi

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Here s my take on this   I d rather not use a bash for loop if I can avoid it  as that takes time to run  If something has to loop  let it be something that was written in a lower level language than a shell script   function array contains     arrayname value   local -A  arr      local IFS    eval  arr     eval printf    q   1          1           return     1 - 0   arr  2          This works by creating a temporary associative array   arr  whose indices are derived from the values of the input array   Note that associative arrays are available in bash 4 and above  so this function won t work in earlier versions of bash   We set  IFS to avoid word splitting on whitespace   The function contains no explicit loops  though internally bash steps through the input array in order to populate printf  The printf format uses  q to ensure that input data are escaped such that they can safely be used as array keys     a   one two  three four    array contains a three  amp  amp  echo BOOYA BOOYA   array contains a two  amp  amp  echo FAIL     Note that everything this function uses is a built-in to bash  so there are no external pipes dragging you down  even in the command expansion   And if you don t like using eval     well  you re free to use another approach   -

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Below is a small function for achieving this  The search string is the first argument and the rest are the array elements   containsElement        local e match   1    shift   for e  do      e       match      amp  amp  return 0  done   return 1     A test run of that function could look like     array   something to search for   a string   test2000     containsElement  a string     array        echo    0   containsElement  blaha     array         echo    1

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Expanding on the above answer from Sean DiSanti  I think the following is a simple and elegant solution that avoids having to loop over the array and won t give false positives due to partial matches  function is in array       local ELEMENT    1       local DELIM         printf    DELIM  s  DELIM        2     grep -q    DELIM   ELEMENT   DELIM       Which can be called like so     haystack   needle1   needle2   aneedle   spaced needle     is in array  needle     haystack        echo    1   is in array  needle1     haystack        echo    0

[arrays] Check if a Bash array contains a value

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