Category Archives: Linux

To connect to MySQL through a tunnel Open a tunnel on your local machine listening on localhost:3307 and forwarding everything to the mysqlserver server on port 3306, and doing it all via the ssh service on the gateway machine. ssh … Continue reading →

If you are using an updated openssh package and suddenly can’t connect to sites that you could before the update, you can add an option to your .ssh/config file (create it if you don’t have one). If you see this … Continue reading →

telnet can be used to connect you to servername on a specified port. You can gather information from the data returned from that connection: telnet servername.com port Then type: HEAD / HTTP/1.0 bash-3.2# telnet 310.210.7.222 80 Trying 310.210.7.222… Connected to … Continue reading →

ping – probes hosts on the attached network link by sending icmp packets sent over IP tcping – reports the reachability and round-trip time of an IP address hosted on the local network arping – probes hosts on the attached … Continue reading →

When a filesystem is created, case-sensitivity and case-preservation is configurable. In Unix filesystems, filenames are usually case-sensitive. Windows is a mish-mash of case-sensitivity: FAT12 filesystem was case-insensitive Windows filesystems (VFAT, FAT32) are not case-sensitive but are case-preserving NTFS is case-sensitive, … Continue reading →

df -Pk | awk ‘ BEGIN {print “Filesystem Mount Point Total GB Avail GB Used GB Used” print “———————————– ————————- ———- ———- ———- —–“} END {print “”} /dev/ || /^[0-9a-zA-Z.]*:\// { printf (“%-35.35s %-25s %10.2f %10.2f %10.2f %4.0f%\n”,$1,$6,$2/1024/1024,$4/1024/1024,$3/1024/1024,$5) }’

sudo dmidecode |grep “Product Name:” |head -1 If the above command doesn’t work: dmidecode |grep -i “vm” will return nothing on a virtual system and something like “VME (Virtual mode extension)” on a host system.

On a Red Hat system, look for the crash command: http://magazine.redhat.com/2007/08/15/a-quick-overview-of-linux-kernel-crash-dump-analysis/

• BASH is much easier to set a prompt that displays the current directory. To do the same in Kornshell is hackish. • Kornshell has associative arrays and BASH doesn’t. Now, the last time I used Associative arrays was… Let … Continue reading →