239 lines
4.1 KiB
HTML
239 lines
4.1 KiB
HTML
<HTML
|
|
><HEAD
|
|
><TITLE
|
|
>Controlling the Size and Appearance of $PWD</TITLE
|
|
><META
|
|
NAME="GENERATOR"
|
|
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
|
|
REL="HOME"
|
|
TITLE="Bash Prompt HOWTO"
|
|
HREF="index.html"><LINK
|
|
REL="UP"
|
|
TITLE="Prompt Code Snippets"
|
|
HREF="c679.html"><LINK
|
|
REL="PREVIOUS"
|
|
TITLE="Number of Processes"
|
|
HREF="x771.html"><LINK
|
|
REL="NEXT"
|
|
TITLE="Laptop Power"
|
|
HREF="x794.html"></HEAD
|
|
><BODY
|
|
CLASS="SECT1"
|
|
BGCOLOR="#FFFFFF"
|
|
TEXT="#000000"
|
|
LINK="#0000FF"
|
|
VLINK="#840084"
|
|
ALINK="#0000FF"
|
|
><DIV
|
|
CLASS="NAVHEADER"
|
|
><TABLE
|
|
SUMMARY="Header navigation table"
|
|
WIDTH="100%"
|
|
BORDER="0"
|
|
CELLPADDING="0"
|
|
CELLSPACING="0"
|
|
><TR
|
|
><TH
|
|
COLSPAN="3"
|
|
ALIGN="center"
|
|
>Bash Prompt HOWTO: </TH
|
|
></TR
|
|
><TR
|
|
><TD
|
|
WIDTH="10%"
|
|
ALIGN="left"
|
|
VALIGN="bottom"
|
|
><A
|
|
HREF="x771.html"
|
|
ACCESSKEY="P"
|
|
>Prev</A
|
|
></TD
|
|
><TD
|
|
WIDTH="80%"
|
|
ALIGN="center"
|
|
VALIGN="bottom"
|
|
>Chapter 11. Prompt Code Snippets</TD
|
|
><TD
|
|
WIDTH="10%"
|
|
ALIGN="right"
|
|
VALIGN="bottom"
|
|
><A
|
|
HREF="x794.html"
|
|
ACCESSKEY="N"
|
|
>Next</A
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
><HR
|
|
ALIGN="LEFT"
|
|
WIDTH="100%"></DIV
|
|
><DIV
|
|
CLASS="SECT1"
|
|
><H1
|
|
CLASS="SECT1"
|
|
><A
|
|
NAME="AEN783"
|
|
></A
|
|
>11.10. Controlling the Size and Appearance of $PWD</H1
|
|
><P
|
|
>Unix allows long file names, which can lead to the value of $PWD being very
|
|
long. Some people (notably the default RedHat prompt) choose to use the
|
|
basename of the current working directory (ie. "giles" if
|
|
$PWD="/home/giles"). I like more info than that, but it's often desirable
|
|
to limit the length of the directory name, and it makes the most sense to
|
|
truncate on the left.</P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="100%"
|
|
><TR
|
|
><TD
|
|
><FONT
|
|
COLOR="#000000"
|
|
><PRE
|
|
CLASS="PROGRAMLISTING"
|
|
># How many characters of the $PWD should be kept
|
|
local pwdmaxlen=30
|
|
# Indicator that there has been directory truncation:
|
|
#trunc_symbol="<"
|
|
local trunc_symbol="..."
|
|
if [ ${#PWD} -gt $pwdmaxlen ]
|
|
then
|
|
local pwdoffset=$(( ${#PWD} - $pwdmaxlen ))
|
|
newPWD="${trunc_symbol}${PWD:$pwdoffset:$pwdmaxlen}"
|
|
else
|
|
newPWD=${PWD}
|
|
fi </PRE
|
|
></FONT
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
><P
|
|
>The above code can be executed as part of PROMPT_COMMAND, and the
|
|
environment variable generated (<TT
|
|
CLASS="VARNAME"
|
|
>newPWD</TT
|
|
>) can then
|
|
be included in the prompt. Thanks to Alexander Mikhailian
|
|
<TT
|
|
CLASS="EMAIL"
|
|
><<A
|
|
HREF="mailto:mikhailian at altern dot org"
|
|
>mikhailian at altern dot org</A
|
|
>></TT
|
|
> who rewrote the code to utilize
|
|
new Bash functionality, thus speeding it up considerably. </P
|
|
><P
|
|
>Risto Juola (risto AT risto.net) wrote to say that he preferred to have the
|
|
"~" in the <TT
|
|
CLASS="VARNAME"
|
|
>$newPWD</TT
|
|
>, so he wrote another version: </P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="100%"
|
|
><TR
|
|
><TD
|
|
><FONT
|
|
COLOR="#000000"
|
|
><PRE
|
|
CLASS="PROGRAMLISTING"
|
|
>pwd_length=20
|
|
|
|
DIR=`pwd`
|
|
|
|
echo $DIR | grep "^$HOME" >> /dev/null
|
|
|
|
if [ $? -eq 0 ]
|
|
then
|
|
CURRDIR=`echo $DIR | awk -F$HOME '{print $2}'`
|
|
newPWD="~$CURRDIR"
|
|
|
|
if [ $(echo -n $newPWD | wc -c | tr -d " ") -gt $pwd_length ]
|
|
then
|
|
newPWD="~/..$(echo -n $PWD | sed -e "s/.*\(.\{$pwd_length\}\)/\1/")"
|
|
fi
|
|
elif [ "$DIR" = "$HOME" ]
|
|
then
|
|
newPWD="~"
|
|
elif [ $(echo -n $PWD | wc -c | tr -d " ") -gt $pwd_length ]
|
|
then
|
|
newPWD="..$(echo -n $PWD | sed -e "s/.*\(.\{$pwd_length\}\)/\1/")"
|
|
else
|
|
newPWD="$(echo -n $PWD)"
|
|
fi</PRE
|
|
></FONT
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
><P
|
|
>Relative speed: the first version takes about 0.45 seconds on an
|
|
unloaded 486SX25. Risto's version takes about 0.80 to 0.95 seconds. The
|
|
variation in this case is due to whether or not truncation is required. </P
|
|
></DIV
|
|
><DIV
|
|
CLASS="NAVFOOTER"
|
|
><HR
|
|
ALIGN="LEFT"
|
|
WIDTH="100%"><TABLE
|
|
SUMMARY="Footer navigation table"
|
|
WIDTH="100%"
|
|
BORDER="0"
|
|
CELLPADDING="0"
|
|
CELLSPACING="0"
|
|
><TR
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="x771.html"
|
|
ACCESSKEY="P"
|
|
>Prev</A
|
|
></TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="index.html"
|
|
ACCESSKEY="H"
|
|
>Home</A
|
|
></TD
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="right"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="x794.html"
|
|
ACCESSKEY="N"
|
|
>Next</A
|
|
></TD
|
|
></TR
|
|
><TR
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
|
>Number of Processes</TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="c679.html"
|
|
ACCESSKEY="U"
|
|
>Up</A
|
|
></TD
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="right"
|
|
VALIGN="top"
|
|
>Laptop Power</TD
|
|
></TR
|
|
></TABLE
|
|
></DIV
|
|
></BODY
|
|
></HTML
|
|
> |