Commands using cat

Using urandom to get random data, deleting non-letters with tr and print the first $1 bytes.

cat without comments

Example: you have a package.txt you want to install on a system. Instead of this:

cat package.txt

package1

package2

package3

You want it to cat out on one line so you can print "yum install package1 package2 package3"

When dealing with system resource limits like max number of processes and open files per user, it can be hard to tell exactly what's happening. The /etc/security/limits.conf file defines the ceiling for the values, but not what they currently are, while

will show you the current values for your shell, and you can set them for new logins in /etc/profile and/or ~/.bashrc with a command like:

But with the variability in when those files get read (login vs any shell startup, interactive vs non-interactive) it can be difficult to know for sure what values apply to processes that are currently running, like database or app servers. Just find the PID via "ps aux | grep programname", then look at that PID's "limits" file in /proc. Then you'll know for sure what actually applies to that process.

work on any debian based GNU/Linux distro

no need for a for loop when cat takes multiple arguments

Count your source and header file's line numbers

For example for java change the command like this

find . -name '*.java' -exec cat {} \;|wc -l

Original submitted version would break if any filenames had whitespaces in them. The command is a Bad Idea anyhow, because you will end up `cat`ing a binary or something else specacularly bad.

The better alternative to #9756.

I don't think I'd ever use the original command, but this one was so bad I had to post this. Sorry.

1. $(ls) is dumb, and will give errors if you have an alias like "ls -Fs"

2. clear is better and more portable than reset state.

3. if you're interested in differences, then use diff, not cat.

poorman's ifstat using just sh and awk. You must change "eth0" with your interface's name.

Best result when file size less than half of RAM size

Hide comments and empty lines, included XML comments,

Very useful for logs

This command shows a sorted list of the IP addresses from which there have been authentication errors via SSH (possible script kiddies trying to gain access to your server), it eliminates duplicates so it's easier to read, but you can remove the "uniq" command at the end, or even do a "uniq -c" to have a count of how many times each IP address shows in the log (the path to the log may vary from system to system)

Play local mp3 file on remote machine's speakers through ssh

with a semicolon text file map, apply multiple replace to a single file

This one is a bit more robust -- the remote machine may not have an .ssh directory, and it may not have an authorized_keys file, but if it does already, and you want to replace your ssh public key for some reason, this will work in that case as well, without duplicating the entry.

you should umount /dev/cdrom before using this cli

pub key in ./ssh/authorized_keys needed because ssh-ed ssh can't ask for the password.