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Disclaimer:
These pages about different languages / apis / best practices were mostly jotted down quckily and rarely corrected afterwards. The languages / apis / best practices may have changed over time (e.g. the facebook api being a prime example), so what was documented as a good way to do something at the time might be outdated when you read it (some pages here are over 15 years old). Just as a reminder. Shell Scripts for linux / unix / macosxUseful linux shell scripts
Multiple Search & Replace (recursive)
#!/usr/bin/sh
if [ $# -lt 3 ] ; then
echo -e "Wrong number of parameters."
echo -e "Usage:"
echo -e " $0 'filepattern' 'search' 'replace'"
exit 1
fi
find ./ -type f -name $1 -exec sed -i "s/$2/$3/" {} \;
Backup of MySql database, suitable for cron jobThis will email the database to the person specified. Suitable to throw into a cron job and let it run once a week.
Prepend an ls entry with something (e.g. the dirname)
meck='theDirectory';ls -1 $meck| while read line; do echo "$meck/$line"; done
Random things in KSH-scriptsSend a mail
subject="the output from adams.txt"
mailx -s "${subject}" dilbert@somewhereelsereally.com wally@somewhereelsereally.com < adams.txt 2> /dev/null
Sub routines
_sendFile()
{
dilbert=$1
wally=$2
}
...
_sendFile arg1 arg2
Command line arguments
while getopts htf:r:m: arguments
do
case $arguments in
h) echo $USAGE;exit;;
f) CALVIN=$OPTARG;;
m) ADAMS=$OPTARG;;
r) DILBERT=$OPTARG;;
t) WALLY='adams';;
esac
done
Paranoia check return code for each command
cleanup() {
echo "Cleanup: Removing $TMPDIR"
rm -r $TMPDIR
}
checkreturn() {
if [ "0" -ne "$1" ]; then
echo "Failed: $1"
cleanup
exit $1
fi
}
zip -r shellscripts_collection.zip
checkreturn $?
Find out which operating systemdilbert@comic >uname -s HP-UX dilbert@comic >rlogin adams dilbert@adams >uname -s AIX dilbert@adams > storeme - push directories to fileScript I used to jump to different directories and add them to a list (cannot recall why I needed to do this, but whatever):dilbert@wally >cat ~/bin/storeme echo $PWD >> /tmp/storeme_list.txt dilbert@wally >pwd /home/dilbert/theFiles/mydir/adams dilbert@wally >storeme dilbert@wally >cd /tmp dilbert@wally >storeme dilbert@wally >cat /tmp/storeme_list.txt /home/dilbert/theFiles/mydir/adams /tmp dilbert@wally > logging script callsWhen first trying to sort out the mess with all hundreds of ksh-scripts at a company that I were, there were loads of calls from script to other scripts that called other scripts and so on. To help out in which order and how the scripts called each other I added these lines to the scripts.It was very helpful for tracking down how the scripts were called, and also a nice way to make sure that I had replaced all scripts afterwards (i.e. when no log files were generated all scripts were obsolete and could be replaced) # ... filename=/tmp/theFiles_stat_`date +"%Y_%m_%d_%H"`.log echo "$0 $1" >> $filename # .... redirect output to file without bufferingscript -q /dev/null python somescript.py | tee -a mylog.log killing process after a certain amount of timeBased on cpu time onlyMake a wrapper and callulomit -t XXbefore calling your command, with XX being the time before kill in seconds. Note: this is just counting cpu time! timeout from coreutilsThis is the way to go rather than your own hack, see some alternatives below if you cannot install timeout for some reasonstimeout 5m mycommand myarg making sleep and then killing itmake a wrapper that kills it after 15 second (note that the sleep will still go on even if the command finish earlier)( mycommand $@ ) & sleep 15 ; kill $! making sleep and then killing it, and kill sleep process if command finishesnot ideal, note that the pid for the sleep is written to a file to keep track of it.( mycommand $@ ) & PID_MYCMD=$! ( (sleep 900 & echo $! >&3 ) 3>/tmp/vspid; kill $PID_MYCMD) & # just so the pid get a chance to be written sleep 2 PID_SLEEP=$(/dev/null alternativeThis one starts for example an application called "dilbert", and will kill it again after 8 seconds.
_exec()
{
TIMEOUT=$1
$2 &
cmd_pid=$!
sleep $TIMEOUT | ( read nothing; kill $cmd_pid 2>/dev/null;);
sleep_pid=$!
wait $cmd_pid
kill -ALRM $sleep_pid 2>/dev/null
}
TIMEOUT=8
_exec $TIMEOUT dilbert
echo "I just killed Dilbert."
Makefile for different OS
all:
@make -f Makefile.`uname` all
clean:
@make -f Makefile.`uname` clean
install:
@make -f Makefile.`uname` install
and create corresponding Makefiles, e.g. Makefile.HP-UX
A sample .profile for KSHThis is the .profile I use on KSH, the interesting parts are the function mycd and the mapping of the UP arrow.The .profile
# history
alias h="fc -l"
alias mroe=more
alias moer=more
alias "cd.."="cd .."
# to have the path echoed instead of in the prompt
function mycd { # function to change working directory
cd $* > /dev/null
echo $PWD
return 0;
}
alias cd=mycd
alias e="emacs -nw"
alias ls="ls -F"
alias sl=ls
alias "ls-l"="ls -l"
alias "ls-al"="ls -al"
alias ll='ls -lp|more'
alias la='ls -al|more'
alias lt='ls -lt|more'
#create files that are readable but not writeable
umask 022
export PATH=$PATH:/home/userid/bin
#Set the prompt
export PS1="$LOGNAME@$HOSTNAME >"
set -o emacs
# History on the Up arrow
alias __A=`echo ""`
# paths for ProC
export ORACLE_HOME=/oracle806
export PATH="$PATH:/oracle806/bin"
# To make sure that @ is not treated as a kill signal (that would cause problems when using SqlPlus)
stty kill ^U
Calculate in bashecho "scale=2;1000 * ( 2 * 60 + 52) + 96 * 10"|bc 172960 Delete files older than three days
find /some/dir/filematch* -type f -mtime +3 -exec rm {} \;
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