Meaning of too many arguments error from if square brackets

Question

I couldn t find any one simple straightforward resource spelling out the meaning of and fix for the following BASH shell error  so I m posting what I found after researching it   The error   -bash     too many arguments   Google-friendly version  bash open square bracket colon too many arguments   Context  an if condition in single square brackets with a simple comparison operator like equals  greater than etc  for example   VARIABLE    some command   if    VARIABLE    0    then     some action fi

User · Answer

Just bumped into this post  by getting the same error  trying to test if two variables are both empty  or non-empty   That turns out to be a compound comparison - 7 3  Other Comparison Operators - Advanced Bash-Scripting Guide  and I thought I should note the following    I used -e thinking it means  empty  at first  but that means  file exists  - use -z for testing empty variable  string  String variables need to be quoted For compound logical AND comparison  either     use two tests and  amp  amp  them           amp  amp          or use the -a operator in a single test        -a          Here is a working command  searching through all txt files in a directory  and dumping those that grep finds contain both of two words    find  usr share doc -name    txt    while read file  do     a1   grep -H  description   file       a2   grep -H  changes   file           -z   a1  -a   -z   a2      amp  amp  echo -e   a1  n  a2      done     Edit 12 Aug 2013  related problem note    Note that when checking string equality with classic test  single square bracket     you MUST have a space between the  is equal  operator  which in this case is a single  equals    sign  although two equals  signs    seem to be accepted as equality operator too   Thus  this fails  silently      if    1          then echo A  else echo B  fi  A   if    1         then echo A  else echo B  fi  A   if    1        amp  amp     1   1      then echo A  else echo B  fi  A   if    1         amp  amp     1    1      then echo A  else echo B  fi  A       but add the space - and all looks good     if    1           then echo A  else echo B  fi  B   if    1            then echo A  else echo B  fi  B   if    1       -a  1     1      then echo A  else echo B  fi  B   if    1        -a  1      1      then echo A  else echo B  fi  B

User · Answer

Another scenario that you can get the    too many arguments or    a  binary operator expected errors is if you try to test for all arguments       if   -z        then     echo  Argument required   fi   It works correctly if you call foo sh or foo sh arg1  But if you pass multiple args like foo sh arg1 arg2  you will get errors  This is because it s being expanded to   -z arg1 arg2    which is not a valid syntax   The correct way to check for existence of arguments is        -eq 0        is the number of arguments

User · Answer

I have had same problem with my scripts  But when I did some modifications it worked for me  I did like this  -  export k   date    k    if    k -ge 16        then exit 0   else      echo  good job for nothing    fi    that way I resolved my problem  Hope that will help for you too

User · Answer

Some times If you touch the keyboard accidentally and removed a space   if     myvar     something    then     do something fi   Will trigger this error message   Note the space before     is required

User · Answer

If your  VARIABLE is a string containing spaces or other special characters  and single square brackets are used  which is a shortcut for the test command   then the string may be split out into multiple words  Each of these is treated as a separate argument    So that one variable is split out into many arguments   VARIABLE    some command       returns  hello world   if    VARIABLE    0    then     fails as if you wrote      if   hello world    0   fi    The same will be true for any function call that puts down a string containing spaces or other special characters     Easy fix  Wrap the variable output in double quotes  forcing it to stay as one string  therefore one argument   For example   VARIABLE    some command   if     VARIABLE     0    then     some action fi    Simple as that  But skip to  Also beware     below if you also can t guarantee your variable won t be an empty string  or a string that contains nothing but whitespace     Or  an alternate fix is to use double square brackets  which is a shortcut for the new test command     This exists only in bash  and apparently korn and zsh  however  and so may not be compatible with default shells called by  bin sh etc    This means on some systems  it might work from the console but not when called elsewhere  like from cron  depending on how everything is configured    It would look like this   VARIABLE    some command   if     VARIABLE    0     then     some action fi    If your command contains double square brackets like this and you get errors in logs but it works from the console  try swapping out the    for an alternative suggested here  or  ensure that whatever runs your script uses a shell that supports    aka new test     Also beware of the    unary operator expected error  If you re seeing the  too many arguments  error  chances are you re getting a string from a function with unpredictable output  If it s also possible to get an empty string  or all whitespace string   this would be treated as zero arguments even with the above  quick fix   and would fail with    unary operator expected   It s the same  gotcha  if you re used to other languages - you don t expect the contents of a variable to be effectively printed into the code like this before it is evaluated   Here s an example that prevents both the    too many arguments and the    unary operator expected errors  replacing the output with a default value if it is empty  in this example  0   with double quotes wrapped around the whole thing   VARIABLE    some command   if      VARIABLE -0      0    then     some action fi     here  the action will happen if  VARIABLE is 0  or empty  Naturally  you should change the 0  the default value  to a different default value if different behaviour is wanted     Final note  Since   is a shortcut for test  all the above is also true for the error test  too many arguments  and also test  unary operator expected

[bash] Meaning of "[: too many arguments" error from if [] (square brackets)

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