[clue] env variables

Tue Jun 25 09:04:38 MDT 2013

When sourcing a file #!/bin/bash has no effect. It looks to me as if it is
seen as a comment. For fun try this:
cat my_fun
#!/bin/foo
export BAR=Hello

Now source it
. my_fun
No error messages. Now
$ echo $BAR
Hello

So you can add #!/bin/bash, to a file you are going to source, but it has
no effect.
Though if you are always going to add the interpreter to the first line
#!/bin/sh is a better choice. It is more portable. It is usually a link to
a default shell, whereas bash is not necessarily installed on all systems.
A lot of embedded systems don't use bash.

A good example of a sourced file on a debian system would be
/lib/init/vars.sh. It is sourced by a good number of the start up scripts.

Steve

On Mon, Jun 24, 2013 at 5:03 PM, Quentin Hartman <qhartman at gmail.com> wrote:

> Just a note that removing the #! statement at the top of the file is
> usually a bad idea. That doesn't directly start a new shell, that tells the
> system (not sure if it's bash itself, or if it's a kernel thing) which
> interpreter to use for the script. You can get weird results if you leave
> that out and make the script executable.
>
> It does though create a new subshell as was mentioned, which always
> happens with script execution (having nothing to do with #!), which is why
> those env_vars don't show up in the parent shell. In order to get them to
> show up in the parent shell, you have to source them from the parent shell:
>
> 04:57 PM:qhartman at qhstation$ cat foo.sh
> #!/bin/bash
> export FOO=bar
>
> CWD:~
> 04:57 PM:qhartman at qhstation$ ./foo.sh
>
> CWD:~
> 04:57 PM:qhartman at qhstation$ echo $FOO
>
>
> CWD:~
> 04:57 PM:qhartman at qhstation$ source foo.sh
>
> CWD:~
> 04:58 PM:qhartman at qhstation$ echo $FOO
> bar
>
>
> If you need to have those vars set outside of the context of the script
> you are running, you need to add or modify those vars in the appropriate
> user's login shell config (usually .bashrc), and then the next time that
> user invokes a shell they will be set how you want.
>
>
> On Mon, Jun 24, 2013 at 3:28 PM, Mark G. Harvey <markgharvey at yahoo.com>wrote:
>
>>
>>
>> so removing #!/bin/bash/ at the top of the script to stay within the same
>> shell session doesn't make any detectable difference
>>
>> I also added sourcing the file where the variables are set ( # source /etc/profile.d/00_jdk.sh
>>  )
>>
>> the variables PATH and JAVA_HOME show up correct when the script is
>> running ... but when finished, the variables are still not changed
>>
>> [root at 87148-mondev01 ~]# echo $PATH
>> /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
>>  ... should be appended with /usr/java/jdk1.7.0_21/bin
>> [root at 87148-mondev01 ~]# echo $JAVA_HOME
>> ... should have an entry /usr/java/jdk1.7.0_21/bin ... but it is blank
>>
>>
>>
>>
>>   ------------------------------
>>  *From:* "dennisjperkins at comcast.net" <dennisjperkins at comcast.net>
>> *To:* CLUE's mailing list <clue at cluedenver.org>
>> *Sent:* Monday, June 24, 2013 2:56 PM
>>
>> *Subject:* Re: [clue] env variables
>>
>> The proper place for these might be in one of the Bash config files.
>>
>> ------------------------------
>> *From: *"Stephen Queen" <svqueen at gmail.com>
>> *To: *"Mark G. Harvey" <markgharvey at yahoo.com>, "CLUE's mailing list" <
>> clue at cluedenver.org>
>> *Sent: *Monday, June 24, 2013 2:37:49 PM
>> *Subject: *Re: [clue] env variables
>>
>> When you add
>> #!/bin/bash
>> to the top of your script, you are starting a new shell. When the script
>> completes, it exits that shell. Instead "source" you environmental
>> variables. Create a file my_env that contains your export commands
>> # cat my_env
>> export JAVA_HOME=/usr/java/jdk1.7.0_21
>> export PATH=$PATH:/usr/java/jdk1.7.0_21/bin
>>
>> Then source the file
>> . my_env
>> (space between . and my_env, does not need to be executable).
>> Now when you
>> # echo $JAVA_HOME
>> usr/java/jdk1.7.0_21
>> #
>>
>> Steve
>>
>>
>>
>>
>> On Mon, Jun 24, 2013 at 1:54 PM, Mark G. Harvey <markgharvey at yahoo.com>wrote:
>>
>> CLUE experts,
>>
>> This puzzle is likely simple for you folks, but it has me stumped.  I've
>> done considerable digging but have found mixed advice.
>>
>> I've created a script to download from a local repo via wget an rpm to
>> install JDK ... no problem there.
>>
>> Here's the part I can't get right ... setting the variables so I can run
>> scripts to install Tomcat ... Any attempt will bomb if it can't find
>> /usr/java/jdk1.7.0_21/bin
>>
>>
>> # set JAVA_HOME variable   ... tried in vain
>> echo "setting JAVA_HOME variable variable for the session"
>> JAVA_HOME=/usr/java/jdk1.7.0_21
>> # export JAVA_HOME variable  ... tried in vain
>> echo "exporting JAVA_HOME variable variable for the session"
>> export JAVA_HOME=/usr/java/jdk1.7.0_21
>> echo "JAVA_HOME variable: $JAVA_HOME"
>>
>> # set PATH variable for the session   ... tried in vain
>> echo "setting PATH variable for the session"
>> PATH=$PATH:/usr/java/jdk1.7.0_21/bin
>> # export PATH variable for the session
>> echo "exporting PATH variable for the subsequent sessions & processes"
>> export PATH=$PATH:/usr/java/jdk1.7.0_21/bin
>> echo "show PATH variable: $PATH"
>>
>> sleep 3  # wait
>>
>> # create script to set JAVA_HOME & PATH variables in
>> /etc/profile.d/00_jdk.sh script for all accounts
>> # use echo command with single quotes to write the literal statement to
>> the script
>> touch /etc/profile.d/00_jdk.sh
>> echo '#!/bin/bash' >> /etc/profile.d/00_jdk.sh
>> echo '# set JAVA_HOME in /etc/profile.d/00_jdk.sh script for all
>> accounts' >> /etc/profile.d/00_jdk.sh
>> echo 'JAVA_HOME=/usr/java/jdk1.7.0_21' >> /etc/profile.d/00_jdk.sh
>> echo '# set PATH in /etc/profile.d/00_jdk.sh script for all accounts' >>
>> /etc/profile.d/00_jdk.sh
>> echo 'PATH=$PATH:/usr/java/jdk1.7.0_21/bin' >> /etc/profile.d/00_jdk.sh
>>
>> sleep 3  # wait
>>
>> echo "review contents of /etc/profile.d/00_jdk.sh"
>> cat /etc/profile.d/00_jdk.sh
>>
>>
>> ... results of install ... added some blank lines for readability ...
>>
>> [root at 87148-mondev01 ~]# ./DEV_install_jdk1.7-1.0.0.sh<http://dev_install_jdk1.7-1.0.0.sh/>
>>
>> installation:  Oracle/Sun jdk 1.7 64-bit
>> remount /tmp with execute privledge
>> changed to /tmp
>> Pulling package from Artifactory Repo Management Server
>> --2013-06-24 13:24:38--
>> https://<RepoHost>/artifactory/simple/ext-release-local/oracle/jdk/7u21-linux/jdk-7u21-linux-x64.rpm
>> Resolving <RepoHost>... 10.33.44.10
>> Connecting to <RepoHost>|10.33.44.10|:443... connected.
>>
>> HTTP request sent, awaiting response... 200 OK
>>
>> Length: 85388149 (81M) [application/x-rpm]
>> Saving to: “jdk-7u21-linux-x64.rpm”
>>
>> 100%[=======================================================================================================================================>]
>> 85,388,149  52.7M/s   in 1.5s
>>
>> 2013-06-24 13:24:40 (52.7 MB/s) - “jdk-7u21-linux-x64.rpm” saved
>> [85388149/85388149]
>>
>> jdk downloaded
>> check /tmp/ contents for jdk
>> -rw-r--r--. 1 root root 85388149 Jun  6 16:46 jdk-7u21-linux-x64.rpm
>> install jdk rpm
>> Preparing...                ###########################################
>> [100%]
>> package jdk-2000:1.7.0_21-fcs.x86_64 is already installed      ........
>> due to subsequent running of this script
>> install jdk complete
>>
>> setting JAVA_HOME variable variable for the session
>> exporting JAVA_HOME variable variable for the session
>>
>> ... when tested in the script, the correct answer shows up ...
>>
>> JAVA_HOME variable: /usr/java/jdk1.7.0_21
>>
>> setting PATH variable for the session
>> exporting PATH variable for the subsequent sessions & processes
>>
>> ... when tested in the script, the correct answer shows up ...
>>
>>
>> show PATH variable:
>> /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin:/usr/java/jdk1.7.0_21/bin:/usr/java/jdk1.7.0_21/bin
>>
>> review contents of /etc/profile.d/00_jdk.sh
>> #!/bin/bash
>> # set JAVA_HOME in /etc/profile.d/00_jdk.sh script for all accounts
>> JAVA_HOME=/usr/java/jdk1.7.0_21
>> # set PATH in /etc/profile.d/00_jdk.sh  script for all accounts
>> PATH=$PATH:/usr/java/jdk1.7.0_21/bin
>> remount /tmp removing execute privledge
>> finished
>>
>>
>> ... after script runs, when tested from CLI, variables not not correct
>> ...
>>
>> [root at 87148-mondev01 ~]# echo $JAVA_HOME
>>
>> [root at 87148-mondev01 ~]# echo $PATH
>> /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
>>
>>
>>
>> [root at 87148-mondev01 ~]# exit
>> logout
>>
>> [vwadmin at 87148-mondev01 ~]$ su -
>> Password:
>>
>>
>> ... now the variable additions show up ... they come from
>> the /etc/profile.d/00_jdk.sh script created as part of the JDK download &
>> install ...
>>
>> [root at 87148-mondev01 ~]# echo $PATH
>>
>> /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/java/jdk1.7.0_21/bin:/root/bin
>>
>> [root at 87148-mondev01 ~]# echo $JAVA_HOME
>> /usr/java/jdk1.7.0_21
>>
>>
>>
>> ... How can I get the variables to be available for the current root
>> session & usable for subsequent installations?  Trying to avoid the logout
>> / login ...
>>
>>
>>
>> Thanks for your help.
>>
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