How to represent multiple conditions in a shell if statement

Question

I want to represent multiple conditions like this   if      g -eq 1 -a   c     123    -o    g -eq 2 -a   c     456         then       echo abc    else       echo efg     fi     but when I execute the script  it shows  syntax error at line 15      unexpected     where line 15 is the one showing if         What is wrong with this condition  I guess something is wrong with the

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bin bash  current usage    df -h   grep  gfsvg-gfslv    awk   print  5     echo  current usage critical usage 6  warning usage 3   if      current usage    -lt   warning usage        then echo OK current usage is  current usage elif      current usage    -ge   warning usage        amp  amp       current usage    -lt   critical usage        then echo Warning  current usage else echo Critical  current usage fi

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Be careful if you have spaces in your string variables and you check for existence  Be sure to quote them properly   if        somepath               otherstring               barstring       then

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In Bash   if       g    1  amp  amp   c    123         g    2  amp  amp   c    456

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g 3   c 133        g c     1123           g c     2456      amp  amp  echo  abc     echo  efg  efg   g 1   c 123        g c     1123           g c     2456      amp  amp  echo  abc     echo  efg  abc

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Classic technique  escape metacharacters    if        g  -eq 1 -a   c     123     -o      g  -eq 2 -a   c     456       then echo abc else echo efg fi   I ve enclosed the references to  g in double quotes  that s good practice  in general   Strictly  the parentheses aren t needed because the precedence of -a and -o makes it correct even without them   Note that the -a and -o operators are part of the POSIX specification for test  aka    mainly for backwards compatibility  since they were a part of test in 7th Edition UNIX  for example   but they are explicitly marked as  obsolescent  by POSIX   Bash  see conditional expressions  seems to preempt the classic and POSIX meanings for -a and -o with its own alternative operators that take arguments     With some care  you can use the more modern    operator  but be aware that the versions in Bash and Korn Shell  for example  need not be identical   for g in 1 2 3 do     for c in 123 456 789     do         if        g  -eq 1  amp  amp    c     123           g  -eq 2  amp  amp    c     456               then echo  g    g  c    c  true          else echo  g    g  c    c  false          fi     done done   Example run  using Bash 3 2 57 on Mac OS X   g   1  c   123  true g   1  c   456  false g   1  c   789  false g   2  c   123  false g   2  c   456  true g   2  c   789  false g   3  c   123  false g   3  c   456  false g   3  c   789  false   You don t need to quote the variables in    as you do with   because it is not a separate command in the same way that   is        Isn t it a classic question    I would have thought so   However  there is another alternative  namely   if     g  -eq 1 -a   c     123           g  -eq 2 -a   c     456    then echo abc else echo efg fi   Indeed  if you read the  portable shell  guidelines for the autoconf tool or related packages  this notation     using      and   amp  amp       is what they recommend   I suppose you could even go so far as   if     g  -eq 1    amp  amp      c     123    then echo abc elif     g  -eq 2    amp  amp      c     456    then echo abc else echo efg fi   Where the actions are as trivial as echoing  this isn t bad   When the action block to be repeated is multiple lines  the repetition is too painful and one of the earlier versions is preferable     or you need to wrap the actions into a function that is invoked in the different then blocks

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Using  bin bash the following will work   if     option     Y           option     y     then     echo  Entered  option  fi

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you can chain more than 2 conditions too     if        1     --usage     -o      1          -o      1     --help       then    printf   033 2J  printf   033 0 0H     cat  lt  lt  EOF PRINT USAGE      0 - Purpose  upsert qto http json data to postgres db     USAGE EXAMPLE       0 -a foo -a bar    EOF PRINT USAGE    exit 1 fi

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In bash for string comparison  you can use the following technique   if    var OP  val     then     echo  statements  fi   Example   var  something  if    var     otherthing     amp  amp     var     everything     amp  amp     var     allthings     then     echo  this will be printed  else     echo  this will not be printed  fi

[bash] How to represent multiple conditions in a shell if statement?

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