Bash, a command line shell is one of the most used pieces of software in my daily work. I like scripting repetitive actions to save a lot time (it brings me great joy!). One of the simplest and easiest customisations is to add a bit of colour to your otherwise boring bash prompt (otherwise known as $PS1):
[ngrogan@localhost:~]$
can be turned in to this:
The thing about Bash is the colour codes to achieve this can look archaic:
I wrote this script recently for a friend in a job who needed to output a certain percentage of a log file, but no more and no less. This was in Linux using bash, so I had a go at writing a solution, which you see below. Posting this up in case it’s useful to anyone else!
# !/bin/sh # Public Domain, by Neil Grogan 2010 # Script
to output last 30% of file by lines
OLDFILE="oldlog.txt"
NEWFILE="newlog.txt"
PERCENT=0.7
#Use wc to count lines
LINES=$(wc -l $OLDFILE | awk '{ print $1}')
#Linespercent = 2 decimal places, lines by percent, round to whole
LINESPERCENT=$(echo "scale=2; $LINES*$PERCENT" | bc | xargs printf "%1.0f" )
# Use tail to get last 30% and output, can use tail -s with sleep time to have it run on sched.
tail -n $LINESPERCENT $OLDFILE >> $NEWFILE