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Full Discussion: command does not return exit status due to tee
Top Forums Shell Programming and Scripting command does not return exit status due to tee Post 302265010 by vgersh99 on Friday 5th of December 2008 11:20:30 AM
Old 12-05-2008
from USENET comp.unix.shell FAQ:
Code:
======================================================================

13. How do I get the exit code of cmd1 in cmd1|cmd2

    First, note that cmd1 exit code could be non-zero and still don't
    mean an error. This happens for instance in

    cmd | head -1

    you might observe a 141 (or 269 with ksh93) exit status of cmd1,
    but it's because cmd was interrupted by a SIGPIPE signal when
    "head -1" terminated after having read one line.

    To know the exit status of the elements of a pipeline
    cmd1 | cmd2 | cmd3

    a. with zsh:

       The exit codes are provided in the pipestatus special array.
       cmd1 exit code is in $pipestatus[1], cmd3 exit code in
       $pipestatus[3], so that $? is always the same as
       $pipestatus[-1].

    b. with bash:

       The exit codes are provided in the PIPESTATUS special array.
       cmd1 exit code is in ${PIPESTATUS[0]}, cmd3 exit code in
       ${PIPESTATUS[2]}, so that $? is always the same as
       ${PIPESTATUS: -1}.

    c. with any other Bourne like shells

       You need to use a trick to pass the exit codes to the main
       shell.  You can do it using a pipe(2). Instead of running
       "cmd1", you run "cmd1; echo $?" and make sure $? makes it way
       to the shell.

       exec 3>&1
       eval `
         # now, inside the `...`, fd4 goes to the pipe
         # whose other end is read and passed to eval;
         # fd1 is the normal standard output preserved
         # the line before with exec 3>&1
         exec 4>&1 >&3 3>&- 
         {
           cmd1 4>&-; echo "ec1=$?;" >&4
         } | {
           cmd2 4>&-; echo "ec2=$?;" >&4
         } | cmd3
         echo "ec3=$?;" >&4
       `

    d. with a POSIX shell

       You can use this function to make it easier:

       run() {
         j=1
         while eval "\${pipestatus_$j+:} false"; do
           unset pipestatus_$j
           j=$(($j+1))
         done
         j=1 com= k=1 l=
         for a; do
           if [ "x$a" = 'x|' ]; then
             com="$com { $l "'3>&-
                         echo "pipestatus_'$j'=$?" >&3
                       } 4>&- |'
             j=$(($j+1)) l=
           else
             l="$l \"\$$k\""
           fi
           k=$(($k+1))
         done
         com="$com $l"' 3>&- >&4 4>&-
                    echo "pipestatus_'$j'=$?"'
         exec 4>&1
         eval "$(exec 3>&1; eval "$com")"
         exec 4>&-
         j=1
         while eval "\${pipestatus_$j+:} false"; do
           eval "[ \$pipestatus_$j -eq 0 ]" || return 1
           j=$(($j+1))
         done
         return 0
       }
       
       use it as:
       
       run cmd1 \| cmd2 \| cmd3
       exit codes are in $pipestatus_1, $pipestatus_2, $pipestatus_3

======================================================================

 

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LEARN ABOUT X11R4

exit

exit(1)                                                            User Commands                                                           exit(1)

NAME

       exit, return, goto - shell built-in functions to enable the execution of the shell to advance beyond its sequence of steps

SYNOPSIS

   sh
       exit [n]

       return [n]

   csh
       exit [ ( expr )]

       goto label

   ksh
       *exit [n]

       *return [n]

DESCRIPTION

   sh
       exit  will  cause the calling shell or shell script to exit with the exit status specified by n. If n is omitted the exit status is that of
       the last command executed (an EOF will also cause the shell to exit.)

       return causes a function to exit with the return value specified by n. If n is omitted, the return status is that of the last command  exe-
       cuted.

   csh
       exit  will cause the calling shell or shell script to exit, either with the value of the status variable or with the value specified by the
       expression expr.

       The goto built-in uses a specified label as a search string amongst commands. The shell rewinds its input as much as possible and  searches
       for a line of the form label: possibly preceded by space or tab characters. Execution continues after the indicated line. It is an error to
       jump to a label that occurs between a while or for built-in command and its corresponding end.

   ksh
       exit will cause the calling shell or shell script to exit with the exit status specified by n. The value will be the  least  significant  8
       bits of the specified status. If n is omitted then the exit status is that of the last command executed. When    exit occurs when executing
       a trap, the last command refers to the command that executed before the trap was invoked. An end-of-file will also cause the shell to  exit
       except for a shell which has the ignoreeof option (See set below) turned on.

       return  causes a shell function or '.' script to return to the invoking script with the return status specified by n. The value will be the
       least significant 8 bits of the specified status.  If n is omitted then the return status is that of the last command executed.  If  return
       is invoked while not in a function or a '.' script, then it is the same as an exit.

       On this man page, ksh(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways:

       1.  Variable assignment lists preceding the command remain in effect when the command completes.

       2.  I/O redirections are processed after variable assignments.

       3.  Errors cause a script that contains them to abort.

       4.  Words,  following a command preceded by ** that are in the format of a variable assignment, are expanded with the same rules as a vari-
           able assignment. This means that tilde substitution is performed after the = sign and word splitting and file name generation  are  not
           performed.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE         |      ATTRIBUTE VALUE        |
       |Availability                 |SUNWcsu                      |
       +-----------------------------+-----------------------------+

SEE ALSO

       break(1), csh(1), ksh(1), sh(1), attributes(5)

SunOS 5.10                                                          15 Apr 1994                                                            exit(1)
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