An and operator for an if statement in Bash

Question

I m trying to create a simple Bash script to check if the website is down and for some reason the  and  operator doesn t work      usr bin env bash  WEBSITE domain com SUBJECT   WEBSITE DOWN   EMAILID  an email com  STATUS   curl -sI  WEBSITE   awk   HTTP  1 1    print  2     STRING   curl -s  WEBSITE   grep -o  string to search   VALUE  string to search   if    STATUS -ne 200    amp  amp       STRING       VALUE      then     echo  Website   WEBSITE is down  status code    STATUS  -   date     mail -s   SUBJECT   EMAILID fi   The  -a  operator also doesn t work   if    STATUS -ne 200   -a      STRING       VALUE       Could you also please advise when to use    single and double square brackets parenthesis

User · Accepted Answer

What you have should work  unless   STATUS  is empty   It would probably be better to do   if        STATUS   -eq 200   2 gt   dev null  amp  amp       STRING         VALUE      then   or  if      STATUS      200    amp  amp       STRING         VALUE      then   It s hard to say  since you haven t shown us exactly what is going wrong with your script   Personal opinion  never use      It suppresses important error messages and is not portable to different shells

User · Answer

Try this   if     STATUS  -ne 100 -a    STRING        VALUE       or  if     STATUS  -ne 100    amp  amp       STRING        VALUE

User · Answer

Try this   if    STATUS -ne 200 -a   STRING       VALUE     then

User · Answer

Quote   The  quot -a quot  operator also doesn t work  if    STATUS -ne 200   -a     quot  STRING quot      quot  VALUE quot      For a more elaborate explanation    and   are not Bash reserved words  The if keyword introduces a conditional to be evaluated by a job  the conditional is true if the job s return value is 0 or false otherwise   For trivial tests  there is the test program  man test   As some find lines like if test -f filename  then foo bar  fi  etc  annoying  on most systems you find a program called   which is in fact only a symlink to the test program  When test is called as    you have to add   as the last positional argument  So if test -f filename is basically the same  in terms of processes spawned  as if   -f filename    In both cases the test program will be started  and both processes should behave identically  Here s your mistake  if    STATUS -ne 200   -a     quot  STRING quot      quot  VALUE quot     will parse to if   some job  the job being everything except the if itself  The job is only a simple command  Bash speak for something which results in a single process   which means the first word     is the command and the rest its positional arguments  There are remaining arguments after the first    Also not     is indeed a Bash keyword  but in this case it s only parsed as a normal command argument  because it s not at the front of the command

[bash] An "and" operator for an "if" statement in Bash

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