How to avoid duplicate operation in .cshrc file?

[yolande_yj]

I have a file to source in the .cshrc file:

source abc.dat

But this file can be sourced only once. If I log out and log in again, this file should not be sourced again. How can I do that? Thanks.

 

[Hughes]

You can create a tempfile in abc.dat:
touch /tmp/.abc.dat_sourced
and detect if this file exists.

 

[yolande_yj]

You can create a tempfile in abc.dat:
touch /tmp/.abc.dat_sourced
and detect if this file exists.

Can you give me instrution step by steip. Thanks a lot.

 

[Hughes]

if ( ! -e /tmp/.abc.dat_sourced ) then
    touch /tmp/.abc.dat_sourced
    source abc.dat
endif

 

[yolande_yj]

how to delete the .abc.dat_sourced file when Linux is closed? Otherwise that file exit, so I can not source the file again when I restart the OS. And what does -e mean?

 

[Hughes]

how to delete the .abc.dat_sourced file when Linux is closed? Otherwise that file exit, so I can not source the file again when I restart the OS. And what does -e mean?

If you system is configured to empty the /tmp directory at startup, you need do nothing to delete .abc.dat_sourced file. Otherwise, you can add a script to the /etc/rcx.d directory to remove the file (x is a number, may be 3).

 

[yolande_yj]

How do I know if the system empty the /tmp folder at startup?
What script should I add?
Thanks

 

[Hughes]

How do I know if the system empty the /tmp folder at startup?
What script should I add?

You can find if /tmp is auto-emptied simply by checking if it contains any files before system restarted.

The script is like this:

#!/bin/sh
if [ -e /tmp/.abc.dat_sourced ]; then
    rm -f /tmp/.abc.dat_sourced >& /dev/null
fi

The exact code and file name depend on your system.

 

[yolande_yj]

My system is Redhat Enterprise AS. Can I use that code? What is the file name? Thanks

 

[Hughes]

My system is Redhat Enterprise AS. Can I use that code? What is the file name? Thanks

You may try to name it "KxxRmAbcSourced" (xx is to-digit number) and put it under director "/etc/rc0.d" or "SxxRmAbcSourced" and put it to dir "/etc/rcn.d", where n is 2, 3 or 5 (I am not sure). If you always log in with X environment, you can find the current runlevel by command "who" (may be with "-s" option, you may find it by "man"), and use the current runlevel number as n.

I have a file to source in the .cshrc file:

source abc.dat

But this file can be sourced only once. If I log out and log in again, this file should not be sourced again. How can I do that?

Another solution is use "who" and/or "last" commands to find if the current log-in is the first log-in after reboot.

#!/bin/sh
mylog=`who -m`
myname=`whoami`
my1stlog=`last | sed -n "/^$myname/ h
/^reboot/ {
x
p
q
}" `
current_login_time=`echo $mylog | cut -d\  -f3-5`
first_login_time=`echo $my1stlog | cut -d\  -f5-7`
[ T"$current_log_time"  = T"$first_login_time ]

Save the above script to "~/bin/IsFirstLogin" (or anything you like), and set it executable by chmod.
Now in your "~/.login" file, add the following lines:

~/bin/IsFirstLogin
if ($status == 0) then
    source abc.dat
endif

Note that I am not sure if the output of "who" and "last" are consistent with all systems. You can try the following two command:

who -m | cut -d\ -f3-5
# you must be in the login shell to try the above line
last | cut -d\ f5-7

You the outputs are not as time strings, you can modify the numbers.
Best regards
Hughes.