Ubuntu – What does this bash escape sequence mean

bashcommand line

I've searched for a way to change terminal title and found this bash command:

echo -ne "\033]0;NEW_TITLE\007"

It works as it have to, but i'm now interested in what this "magic symbols" mean and how it works.

Best Answer

That uses an XTerm control sequence. echo with -e interprets certain sequences in the string given, in this case \033 became Esc, and \007 is the ASCII bell character (see man 7 ascii).

An Esc (represented as ^]) followed by ] is, in XTerm parlance, an Operating System Control code. Terminals which support it interpret it as given in the above link:

OSC Ps ; Pt ST
OSC Ps ; Pt BEL
          Set Text Parameters.  For colors and font, if Pt is a "?", the
          control sequence elicits a response which consists of the con-
          trol sequence which would set the corresponding value.  The
          dtterm control sequences allow you to determine the icon name
          and window title.
            Ps = 0  -> Change Icon Name and Window Title to Pt.
            Ps = 1  -> Change Icon Name to Pt.
            Ps = 2  -> Change Window Title to Pt.

OSC being ^]], the Ps in this case is 0, which sets Pt, in this case NEW_TITLE, as the terminal title.

Ubuntu – What does $PATH mean

Run in a terminal:

echo $PATH

printf "%s\n" "$PATH"

what you see is a list of directories, looking like:

/home/jacob/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games

If you put an executable in either one of these directories, you do not need to set the path to the executable / script, but you can run it by its name as a command.

Executables in $PATH should not have a language extension by convention (although they would work)

Editing your $PATH variable

You can (permanently) add a directory to $PATH by adding the following line to your ~/.profile file (invisible by default, press Ctrl+H in the file manager to make it visible):

export PATH=$PATH:/path/to/dir

More usefull information on environment variables

(such as $PATH) can be found here (thanks for the suggestions @Letizia)

Ubuntu – How to compute the mean from ASCII file data in bash

Another way, using sed and bc:

sed 's/^/n+=1;x+=/;$ascale=1;x/n' timemeasurements.txt | bc

The sed expression converts the input to something like this:

n+=1;x+=2.5
n+=1;x+=3.5
n+=1;x+=2.0
scale=1;x/n

This is piped to bc which evaluates it line-by-line.

Best Answer

Related Solutions

Ubuntu – What does $PATH mean

Editing your $PATH variable

More usefull information on environment variables

Ubuntu – How to compute the mean from ASCII file data in bash

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