Commands tagged echo

Run the alias command, then issue

and resize your terminal window (putty/console/hyperterm/xterm/etc) then issue the same command and you'll understand.

Insructs the shell that if LINES is not set or null to use the output from `tput lines` ( ncurses based terminal access ) to get the number of lines in your terminal. But furthermore, in case that doesn't work either, it will default to using the default of 80.

The default for TAIL is to output the last 10 lines, this alias changes the default to output the last x lines instead, where x is the number of lines currently displayed on your terminal - 7. The -7 is there so that the top line displayed is the command you ran that used TAIL, ie the prompt.

Depending on whether your PS1 and/or PROMPT_COMMAND output more than 1 line (mine is 3) you will want to increase from -2. So with my prompt being the following, I need -7, or - 5 if I only want to display the commandline at the top. ( http://www.askapache.com/linux/bash-power-prompt.html )

275MB/748MB

[7995:7993 - 0:186] 06:26:49 Thu Apr 08 [askapache@n1-backbone5:/dev/pts/0 +1] ~

In most shells the LINES variable is created automatically at login and updated when the terminal is resized (28 linux, 23/20 others for SIGWINCH) to contain the number of vertical lines that can fit in your terminal window. Because the alias doesn't hard-code the current LINES but relys on the $LINES variable, this is a dynamic alias that will always work on a tty device.

change the time that you would like to have as print interval

and just use it to say whatever you want to

export THISOS="`uname -s`"

if [ "$THISOS" = "SunOS" ]

then

export THISRELEASE="`uname -r`"

ping1() { ping -s $1 56 1 | egrep "^64"; }

elif [ "$THISOS" = "AIX" ]

then

export THISRELEASE="`uname -v`.`uname -r`"

ping1() { ping -w ${2:-1} $1 56 1 | egrep "^64"; }

elif [ "$THISOS" = "Linux" ]

then

export THISRELEASE="`uname -r`"

ping1() { ping -c 1 -w ${2:-1} $1 | egrep "^64"; }

fi

I have used single packet, and in a silent mode with no display of ping stats. This is with color and UI improvement to the http://www.commandlinefu.com/commands/view/10220/check-if-a-machine-is-online. It is as per the enhancements suggested.

PING

parameters

c 1 limits to 1 pinging attempt

q makes the command quiet (or silent mode)

/dev/null 2>&1 is to remove the display

&& echo ONLINE is executed if previous command is successful (return value 0)

|| echo OFFLINE is executed otherwise (return value of 1 if unreachable or 2 if you're offline yourself).

I personally use this command as an alias with a predefined machine name but there are at least 2 improvements that may be done.

Asking for the machine name or IP

Escaping the output so that it displays ONLINE in green and OFFLINE in red (for instance).

Ever need to get some text that is a specific number of characters long? Use this function to easily generate it! Doesn't look pretty, but sure does work for testing purposes!

Also lists hidden files, current dir and topdir.

This is mostly for my own notes but this command will compute a md5 message digest from the command line.

You can also replace md5sum with other checksum commands (e.g., sha1sum)

uses the -u switch for UTC

Another way could be

Fast and excludes words with apostrophes. For ubuntu, you can use wamerican or wbritish dictionaries, installable through aptitude.

Generates a password using symbols, alpha, and digits. No repeating chars.

This is just a slight alternative that wraps all of #7917 in a function that can be executed

Are the two strings anagrams of one another?

sed splits up the strings into one character per line

the result is sorted

cmp compares the results

Note: This is not pretty. I just wanted to see if I could do it in bash.

Note: It uses fewer characters than the perl version :-)

An alternative which does not require to be root

Like 7171, but fixed typo, uses fewer variables, and even more cryptic!

cryptic version

Lightweight alternative with case

displays current time in "binary clock" format

(loosely) inspired by: http://www.thinkgeek.com/homeoffice/lights/59e0/

"Decoding":

8421

.... - 1st hour digit: 0

*..* - 2nd hour digit: 9 (8+1)

.*.. - 1st minutes digit: 4

*..* - 2nd minutes digit: 9 (8+1)

Prompt-command version:

PROMPT_COMMAND='echo "10 i 2 o $(date +"%H%M"|cut -b 1,2,3,4 --output-delimiter=" ") f"|dc|tac|xargs printf "%04d\n"|tr "01" ".*"'

if you're using wildcards * or ? in your command, and if you're deleting, moving multiple files, it's always safe to see how those wildcards will expand. if you put "echo" in front of your command, the expanded form of your command will be printed. It's better safe than sorry.

This uses some tricks I found while reading the bash man page to enumerate and display all the current environment variables, including those not listed by the 'env' command which according to the bash docs are more for internal use by BASH. The main trick is the way bash will list all environment variable names when performing expansion on ${!A*}. Then the eval builtin makes it work in a loop.

I created a function for this and use it instead of env. (by aliasing env).

This is the function that given any parameters lists the variables that start with it. So 'aae B' would list all env variables starting wit B. And 'aae {A..Z} {a..z}' would list all variables starting with any letter of the alphabet. And 'aae TERM' would list all variables starting with TERM.

And my printenv replacement is:

From: http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

Use bc for decimals...

Grabs the cmdline used to execute the process, and the environment that the process is being run under. This is much different than the 'env' command, which only lists the environment for the shell. This is very useful (to me at least) to debug various processes on my server. For example, this lets me see the environment that my apache, mysqld, bind, and other server processes have.

Here's a function I use:

From my .bash_profile at http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

While going through the source code for the well known ps command, I read about some interesting things.. Namely, that there are a bunch of different fields that ps can try and enumerate for you. These are fields I was not able to find in the man pages, documentation, only in the source.

Here is a longer function that goes through each of the formats recognized by the ps on your machine, executes it, and then prompts you whether you would like to add it or not. Adding it simply adds it to an array that is then printed when you ctrl-c or at the end of the function run. This lets you save your favorite ones and then see the command to put in your .bash_profile like mine at : http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

Note that I had to do the exec method below in order to pause with read.

t ()

{

local r l a P f=/tmp/ps c='command ps wwo pid:6,user:8,vsize:8,comm:20' IFS=' ';

trap 'exec 66

exec 66 $f && command ps L | tr -s ' ' >&$f;

while read -u66 l >&/dev/null; do

a=${l/% */};

$c,$a k -${a//%/} -A;

yn "Add $a" && P[$SECONDS]=$a;

done

}