Some brief notes I made on sending HTML mail (with an optional attachment) from the command line.
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$ cat ./mailheader To: you@there.com From: me@here.com MIME-Version: 1.0 Content-Type: text/html; charset=us-ascii Subject: Hello $ cat ./mailbody <center><h1>Hello</h1></center> $ cat ./mailheader ./mailbody | /usr/lib/sendmail -t # send an attachment too? $ ( cat ./mailheader ./mailbody && uuencode attachment.txt attachment.txt ) | /usr/lib/sendmail -t |
This is easiest done with lsof. On Solaris you can use pfiles, and you may also find netstat -anlp on Linux useful.
First, find the PID of the process you’re interested in
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# ps -ef | grep '[v]m' root 32702 1 0 Mar08 ? 00:00:00 /usr/bin/vmpsd |
Then, run lsof against the PID
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# lsof -p 32702 COMMAND PID USER FD TYPE DEVICE SIZE NODE NAME vmpsd 32702 root cwd DIR 9,1 4096 2 / vmpsd 32702 root rtd DIR 9,1 4096 2 / vmpsd 32702 root txt REG 9,1 23708 881217 /usr/bin/vmpsd vmpsd 32702 root mem REG 0,0 0 [heap] (stat: No such file or directory) vmpsd 32702 root mem REG 9,1 1184892 1024170 /lib32/libc-2.4.so vmpsd 32702 root mem REG 9,1 124785 1024169 /lib32/ld-2.4.so vmpsd 32702 root 0u CHR 136,0 2 /dev/pts/0 (deleted) vmpsd 32702 root 1u CHR 136,0 2 /dev/pts/0 (deleted) vmpsd 32702 root 2u CHR 136,0 2 /dev/pts/0 (deleted) vmpsd 32702 root 3u IPv4 4214826 UDP *:1589 vmpsd 32702 root 4u unix 0xffff81007d816300 4214827 socket |
Port 1589/UDP, that’s the information we wanted.
We all know how easy it is to grep for something OR something_else:
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egrep 'something|something_else' filename |
However, there’s no elegant way to grep for something AND something_else:
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# This works, but is ugly grep 'something' filename | grep 'something_else' # This works, but searchterms must appear in the same order within the file grep 'something.*something_else' filename |
Easiest way around this (and most elegant) is with awk:
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awk '$0 ~ /something/ && $0 ~ /something_else/ 1;' filename |
If it is a file that is called ‘ ‘, i.e. a single space, you can delete it a couple of ways:
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$ touch \ $ ls -la total 4 -rw-rw-r-- 1 foo bar 0 Nov 24 11:26 drwxrwxr-x 2 foo bar 512 Nov 24 11:26 . drwxr-xr-x 10 foo bar 1024 Nov 24 11:25 .. $ rm ' ' $ ls -la total 4 drwxrwxr-x 2 foo bar 512 Nov 24 11:26 . drwxr-xr-x 10 foo bar 1024 Nov 24 11:25 .. $ touch \ $ ls -la total 4 -rw-rw-r-- 1 foo bar 0 Nov 24 11:26 drwxrwxr-x 2 foo bar 512 Nov 24 11:26 . drwxr-xr-x 10 foo bar 1024 Nov 24 11:25 .. $ ls -lia total 4 320 -rw-rw-r-- 1 foo bar 0 Nov 24 11:26 319 drwxrwxr-x 2 foo bar 512 Nov 24 11:26 . 6 drwxr-xr-x 10 foo bar 1024 Nov 24 11:25 .. $ find . -inum 320 -exec rm {} \; $ ls -la total 4 drwxrwxr-x 2 foo bar 512 Nov 24 11:26 . drwxr-xr-x 10 foo bar 1024 Nov 24 11:25 .. |
Also, it might actually be some kind of control character … observe:
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$ touch ^G (CTRL-V CTRL-G) $ ls -la total 4 -rw-rw-r-- 1 foo bar 0 Nov 24 11:27 drwxrwxr-x 2 foo bar 512 Nov 24 11:27 . drwxr-xr-x 10 foo bar 1024 Nov 24 11:25 .. $ ls -lba total 4 -rw-rw-r-- 1 foo bar 0 Nov 24 11:27 \007 drwxrwxr-x 2 foo bar 512 Nov 24 11:27 . drwxr-xr-x 10 foo bar 1024 Nov 24 11:25 .. |
Easy to remove with the same find . -inum technique above.
If the file starts with a - character, e.g.:
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$ ls -l -rw-rw-rw-- 1 foo bar 0 Nov 24 11:27 -foo |
try removing it:
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$ rm -foo |
Obviously it’ll whinge about -foo not being an option … so:
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$ rm -- -foo |
That’ll do it. -- tells the command to stop interpreting arguments as options. You can use this technique with other commands too, e.g. mv, file, etc.
Disclaimer: This post was originally posted in 2008 as an article on the now-defunct website zazzybob.com. While the software version and actual commands used may vary, the concepts are still similar and give a general idea of how to approach a given problem.
The default BIND installation in Solaris 10 does not run in a chroot environment, which is an obvious security risk. Starting BIND to run in a chroot environment is a no-brainer, but getting it to managed by SMF in Solaris 10 requires a bit more work …
Note: This tip assumes that you’ve checked the filesystem for legitimate files called core before running the scripts/commands contained herein! See the bottom of this article for how to do that.
Coredumps are created when a program crashes and dumps the contents of memory at the time of the crash to disk. Left unchecked, coredumps can quickly become a problem, consuming vast amounts of disk space.
You can find and remove core dumps with a command such as:
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find / -name "core" -exec rm {} \; |
This is fine for a quick fix, but for a longer-lasting solution you can do one of two things. If your OS/Shell support it, you can add the following line to /etc/profile for POSIX compliant shells to disable core dump generation:
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ulimit -c 0 2>/dev/null |
(For the C shell, add the line “limit coredumpsize 0” to /etc/csh.login).
If your OS/Shell doesn’t support this, you can still tackle the problem as it happens. Most core files appear in users home directories. Running a quick script such as:
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#!/bin/sh find / -name "core" -print > corelist while read corefile do cat /dev/null > $corefile chmod 444 $corefile done < corelist exit 0 |
will ensure that any core file on the system is truncated to zero bytes and marked read-only, so that the core file cannot be re-created and thus will never be larger than 0 bytes. Obviously, this is a very kludgy solution, and to work efficiently, you’d need a zero byte core file in everyone’s home directory (and anywhere else on the system coredumps are found), but suffices on very old systems where ulimit isn’t available. Run from cron on a nightly basis, this can be a very useful technique on old systems.
A much more robust way of searching for and deleting core dumps is with a command like:
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find . -name "core" -type f -exec file {} \; |\ awk 'BEGIN { FS = ":" } $2 ~ /core file/ { print $1 }' | xargs rm -f |
If you want to be cautious, then change the rm -f to rm -i.
If you’re using a system other than Solaris, you may need to modify the regex in the awk command to match whatever the output of the file command gives you when executed against a core dump.
We can see this in action here…
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$ sleep 100 & [3] 3244 $ kill -11 %3 $ [3] + Segmentation Fault $ ls core $ mkdir tmp $ touch tmp/core $ file tmp/core tmp/foo: empty $ find . -name "core" -type f -exec file {} \; |\ > awk 'BEGIN { FS = ":" } $2 ~ /core file/ { print $1 }' | xargs rm -f $ ls $ ls tmp core |
As you can see, it’s only removed the true core dump.
Recent versions of Solaris come with a suite of tools known as the “/proc” tools, which list and/or modify process information in the kernel-maintained /proc filesystem. One of these tools, pcred, can be used to change (among other things) the UID of a running process, e.g.:
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# ps -ef | grep sleep root 25853 22210 0 09:55:53 pts/10 0:00 grep sleep kevin 24088 24081 0 09:50:53 pts/11 0:00 sleep 10000000 # pcred -u 123 24088 # ps -ef | grep sleep mrbig 24088 24081 0 09:50:53 pts/11 0:00 sleep 10000000 root 25911 22210 0 09:56:02 pts/10 0:00 grep sleep |
man proc, you’ll receive the manual page for the /proc tools - highly useful.
Just a quick one. If you think emacs is a bunch of crap (like me), you’ll hate the way that tcsh defaults to using this Meta-key-ridden abomination for line editing. Let’s enable vi-mode line editing:
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kevin@foo> bindkey -v |
Ahhh, that’s better.
To make this persistent, just add it to ~/.cshrc_local:
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kevin@foo> echo "bindkey -v" >> ~/.cshrc_local |
Job done. Better yet, don’t use tcsh!
It’s easy to telnet to port 80 on a “standard” non-SSL webserver, and issue a GET / in order to verify that the webserver is responding correctly. But how to do it over SSL? Just use the s_client command via the openssl tool.
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# openssl s_client -connect www.example.com:443 |
GET / to test the webservers operation.
You can also use this tool to test other SSL-enabled services (such as IMAPS/POP3S).
Simple one-liner to remove empty files older than 7 days:
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# find . -type f -mtime +7 -size 0c | xargs rm |