Commands tagged bash

The file .my.cnf located at user's home directory is used for mysql login. If this file exists, then

can be replaced with

It saves you from typing!

This is valid for mysqladmin and mysqldump commands as well.

Sometimes you want to know the summary of the sizes of directories without seeing the details in their subdirectories. Especially if it is going to just scroll off the screen. This one liner summarizes the disk usage of any number of directories in a directory without giving all the details of whats happening underneath.

explanation:

grep -- displays process ids

-v -- negates the matching, displays all but what is specified in the other options

-u -- specifies the user to display, or in this case negate

The process loops through all PIDs that are found by pgrep, then orders a forced kill to the processes in numerical order, effectively killing the parent processes first including the shells in use which will force the users to logout.

Tested on Slackware Linux 12.2 and Slackware-current

Example: To store the function addfunction after you have defined it:

If you want to operate on a set of items in Bash, and at least one of them contains spaces, the `for` loop isn't going to work the way you might expect. For example, if the current dir has two files, named "file" and "file 2", this would loop 3 times (once each for "file", "file", and "2"):

Instead, use a while loop with `read`:

After a command is run in bash, !$ is set to the last (space-delimited) argument of the command. Great for running several commands against the same file in a row.

The brace expansion also allows you to count backward:

for i in {15..1}; do echo $i; done

You can also use this construct to create new file or new directory:

mkdir dir{1..3} # Same as mkdir dir1 dir2 dir3

Displays all information about your battery. for just capacity, try replacing cat with

Battery number might be BAT0 instead of BAT1. Just run

and find out what folder is in that directory and replace that name with BAT1

If you would like to edit a previous command, which might be long and complicated, you can use the fc (I think it stands for fix command). Invoke fc alone will edit the last command using the default editor (specified by $FCEDIT, $EDITOR, or emacs, in that order). After you make the changes in the editor, save and exit to execute that command. The fc command is more flexible than what I have described. Please 'man bash' for more information.

CDPATH tells the cd command to look in this colon-separated list of directories for your destination. My preferred order are 1) the current directory, specified by the empty string between the = and the first colon, 2) the parent directory (so that I can cd lib instead of cd ../lib), 3) my home directory, and 4) my ~/projects directory.

Alias two dots to move to parent directory. Put it into your .bashrc or .profile file.

The output of "echo $PATH" is hard to read, this is much easier. The parentheses ensure that the change to the input field separator (IFS) only happens the the sub shell and not affecting the current shell.

You're running a script, command, whatever.. You don't expect it to take long, now 5pm has rolled around and you're ready to go home... Wait, it's still running... You forgot to nohup it before running it... Suspend it, send it to the background, then disown it... The ouput wont go anywhere, but at least the command will still run...

Hold ctrl and press z to pause the current thread. Run

to resume it.

NOT MINE! Taken from hackzine.com blog.

It creates a tree-style output of all the (sub)folders and (sub)files from the current folder and down(deeper)

Quoting some of hackzine's words

"Murphy Mac sent us a link to a handy find/sed command that simulates the DOS tree command that you might be missing on your Mac or Linux box. [..split...] Like most things I've seen sed do, it does quite a bit in a single line of code and is completely impossible to read. Sure it's just a couple of substitutions, but like a jack in the box, it remains a surprise every time I run it."

Replace (as opposed to insert) hex opcodes, data, breakpoints, etc. without opening a hex editor.

HEXBYTES contains the hex you want to inject in ascii form (e.g. 31c0)

OFFSET is the hex offset (e.g. 49cf) into the binary FILE

I put that line in my .bash_profile (OS X) and .bashrc (Linux).

Here is a summary of what the \char means: n=new line, u=user name, h=host, !=history number, w=current work directory

The \[\e[32m\] sequence set the text to bright green and \[\e[0m\] returns to normal color.

For more information on what you can set in your bash prompt, google 'bash prompt'

This is the result of a several week venture without X. I found myself totally happy without X (and by extension without flash) and was able to do just about anything but watch YouTube videos... so this a the solution I came up with for that. I am sure this can be done better but this does indeed work... and tends to work far better than YouTube's ghetto proprietary flash player ;-)

Replace $i with any YouTube ID you want and this will scrape the site for the _real_ URL to the full quality .FLV file on Youtube's server and will then will hand that over to mplayer (or vlc or whatever you want) to be streamed.

In some browsers you can replace $i with just a % or put this in a shell script so all YouTube IDs can be handed directly off to your media player of choice for true streaming without the need for Flash or a downloader like clive. (I do however fully recommend clive if you wish to archive videos instead of streaming them)

If any interest is shown I would be more than happy to provide similar commands for other sites. Most streaming flash players use similar logic to YouTube.

Edit: 05/03/2011 -

Updated line to work with current YouTube. It could be a lot prettier but I will probably follow up with another update when I figure out how to get rid of that pesky Grep. Sed should take that syntax... but it doesn't.

Original (no longer working) command:

mplayer -fs $(echo "http://youtube.com/get_video.php?$(curl -s $youtube_url | sed -n "/watch_fullscreen/s;.*\(video_id.\+\)&title.*;\1;p")")

with discard wilcards in bash you can "tail" newer logs files to see what happen, any error, info, warn...

This will print out the third column of every line in FILE. Useful for many files in /proc or *csv data.

Useful if you want get all the md5sum of files but you want exclude some directories. If your list of files is short you can make in one command as follow:

Alternatively you can specify a different command to be executed on the resulting files.

Needed to get the Mac of various devices on a solaris box, but didn't have root. This command used awk to display the Network device, the IP, and the MAC a line at a time.