Setting an environment variable in csh

Question

I have the following line at the first line in my script file:

#!/bin/sh

So I'm using csh.(?)

I wanto assign the output of the following to an environment variable:

echo $MYUSR | awk '{print substr($0,4)}'

I try:

set $MYVAR = echo $MYUSR | awk '{print substr($0,4)}'

But it doesn't work, How can I do it? I want to do it in a sh file.

I'm curious, did you mean for your script to be sh or csh? — dldnh
– dldnh, Commented Mar 17, 2012 at 10:07

shellter · Accepted Answer · 2012-03-16 15:18:22Z

2

Your script should look like

 #!/bin/csh

 set MYVAR = `echo $MYUSR | awk '{print substr($0,4)}'`

 echo $MYVAR

I don't have a way to test this right now, let me now if it doesn't work.

If you've inherited the basis of your script from someone else, with the #!/bin/sh, then you have to find out if /bin/sh is really the bourne shell, or if it is a link to /bin/bash

You can tell that by doing

   ls -l /bin/sh /bin/bash

if you get back information on files where the size is exactly the same, the you're really using bash, but called as /bin/sh

So try these 2 solutions

   MYVAR=$(echo $MYUSR | awk '{print substr($0,4)}')
   echo $MYVAR

AND

   MYVAR=``echo $MYUSR | awk '{print substr($0,4)}``  
   echo $MYVAR

   # arg!! only one pair of enclosing back-ticks needed, 
   # can't find the secret escape codes to make this look exactly right.

in all cases (csh) included, the back-ticks AND the $( ... ) are known as command substitution. What every output comes from running the command inside, is substituted into the command line AND then the whole command is executed.

I hope this helps.

edited Mar 16, 2012 at 15:18

answered Mar 16, 2012 at 14:57

shellter

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9 Comments

alwbtc Over a year ago

I get this: sh-3.1$ ls -l /bin/sh /bin/bash -rwxr-xr-x 1 root root 785856 Jul 12 2006 /bin/bash lrwxrwxrwx 1 root root 4 Jun 15 2010 /bin/sh -> bash Do I use bash? should I export MYVAR in the end? Thanks

shellter Over a year ago

yes, your /bin/sh and /bin/bash are really the same program. In some systems, using /bin/sh limits the features available in /bin/bash to those in Bourne shell (/bin/sh on older Unix systems like Solaris/HP/AIX, et.al). If you are doing this for yourself, you definitely want to use bash going forward. If you're doing it for a job, you have to find out if it is OK to do so.

shellter Over a year ago

...... You only need to export variables that are required for use inside a sub-shell environment. You can either test if you program works without the export OR you can just go ahead and export it. That being said, I don't recommend exporting every variable, as that increases memory usage for no real good purpose.

alwbtc Over a year ago

I tried MYVAR = $(echo $MYUSR | awk '{print substr($0,21)}') export MYVAR but it doesnt display anythin when I do echo $MYVAR in the application xterm, what went wrong?

shellter Over a year ago

what is in your var $MYUSR ? ALSO no spaces allowed around '=', is that a typo or did you actually run with spaces around '='? AND, I'm assuming that you really had a export MYVAR on a separate line? If not, you should use MYVAR=$(echo $MYUSR | awk '{print substr($0,21)}') ; export MYVAR (note the semicolon). Good luck.

|

dldnh · Accepted Answer · 2012-03-16 14:57:03Z

0

if it's /bin/sh it's bourne shell or bash, and use back quotes to execute something and this to assign that...

MYVAR=`echo $MYUSR | awk ...`

answered Mar 16, 2012 at 14:57

dldnh

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2 Comments

alwbtc Over a year ago

when I do echo $SHELL I get /bin/csh. When I do MYVAR = echo $CARMUSR | awk '{print substr($0,21)}'`` I get "command not found" error.

dldnh Over a year ago

your command-line shell might be csh, but the script you're writing, if it has /bin/sh after the #!, will run in bourne shell or bash.

shellter · Accepted Answer · 2012-03-16 15:15:39Z

0

That script first line indicates that it should be interpreted by the Bourne shell (sh), not csh. Change it to

#!/bin/csh

edited Mar 16, 2012 at 15:15

shellter

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answered Mar 16, 2012 at 14:57

John Retterer

1

2 Comments

John Retterer Over a year ago

Oops, the initial hash mark didn't make it through the html. The change is substitute csh for sh.

shellter Over a year ago

In the future, use 4 spaces in front of code samples, then the '#' looses its meaning (inside S.O.) to make the text bold. Also note at top of text input box, there are a series of editing tools, including {} to auto-indent (With 4 spaces) a block of text, so it will be presented as-is, i.e. for code samples, program output, etc. Good luck and keep posting.

mtk · Accepted Answer · 2012-05-19 11:05:13Z

0

The first line of your code shows clearly you are not using a csh. You are using a plain sh environment/shell. You have 2 options:

Either change the first line to #!/bin/csh OR
Keeping first line unchanged, update the code for setting the variable.
```
MYVAR=`echo $MYUSR | awk '{print substr($0,4)}`
echo $MYVAR
```

Let me know, if you get any error.

answered May 19, 2012 at 11:05

mtk

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