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47.3 Conditional Statements with if

.login and .cshrc files" 1070 is the use of conditionals ( if statements). This article explains the syntax of if statements. Article 47.4 of explains the syntax of the expressions you can test with an if .

The if command is used to begin a conditional statement. The simple format is:

if (

expr

) 

cmd

There are three other possible formats, shown side-by-side:

if (

expr

) then   if (

expr

) then   if (

expr

) then
   

cmds

      

cmds1

      

cmds1


endif   else   else if (

expr

) then
      

cmds2

      

cmds2


   endif   else
         

cmds3


      endif

In the simplest form, execute cmd if expr is true; otherwise do nothing (redirection still occurs; this is a bug). In the other forms, execute one or more commands. If expr is true, continue with the commands after then ; if expr is false, branch to the commands after else (or after the else if and continue checking). For example, the following if clause will take a default action if no command-line arguments are given:

if ($#argv == 0) then
   echo "No filename given. Sending to Report."
   set outfile = Report
else
   set outfile = $argv[1]
endif

For more examples, see article 47.4 .

- DG from O'Reilly & Associates' UNIX in a Nutshell (SVR4/Solaris)


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