Handy BASH reference ( link)
robust script writing ( link)
lockfile lockfile a.lock
#do stuff hererm -f a.lock
date ( link)
Spicing up your shell script ( link)
parameters ( link)
Tutorials
timing commands /usr/bin/time -o outfile -v command # prints verbose stats into outfile from running command
BASH internal variables ( link)
for i in 1 2 3 4 5
do
echo "Welcome $i times"
done
for i in {1..5}
do
echo "Welcome $i times"
done
for i in {0..10..2} # skip by 2s, only BASH 4.0+
do
echo "Welcome $i times"
done
for (( c=1; c<=5; c++ ))
do
echo "Welcome $c times"
done
for i in 1 2 3 4 5
do
echo "Welcome $i times"
if ( condition )
then
break
fi
done
# continue - jumps to beginning of loop with next iteration
for file in /etc/*
do
if [ "${file}" == "/etc/resolv.conf" ]
then
echo "file ${file} found!"
fi
done
files="$@"
for f in $files
do
if [ -f ${f} ]
then
echo "{f} is a file"
else
echo "${f} is not a file"
fi
done
$ read -p "Press enter to quit..." # reads one line
$ read -n 1 -p "Press any key to start backup..." # reads only one char
$ read -n 1 -s -t 5 # reads one char, no echo, 5sec timeout
$ read -n 1 -s key # reads one char, no echo, stores in ${key}
terminate commands after timeout ( link) #!/bin/bash
# License: BSD License
# As Example we start 3 production processes in the background
# always record PID in PRODPID
sleep 50 &
PRODPID[1]=$!
sleep 20 &
PRODPID[2]=$!
# multiple processes in a subshell as example
(sleep 20 ; sleep 10 ; sleep 5)&
PRODPID[3]=$!
export PRODPID
# record own PID
export PID=$$
# define exit function
exit_timeout() {
echo "Timeout. These processes are not finished:"
for i in ${PRODPID[@]} ; do
ps -p $i |grep -v "PID TTY TIME CMD"
if [ $? == 0 ] ; then
# process still alive
echo "Sending SIGTERM to process $i"
kill $i
fi
done
# timeout exit
exit
}
# Handler for signal USR1 for the timer
trap exit_timeout SIGUSR1
# starting timer in subshell. It sends a SIGUSR1 to the father if it timeouts.
export TIMEOUT=30
(sleep $TIMEOUT ; kill -SIGUSR1 $PID) &
# record PID of timer
TPID=$!
# wait for all production processes to finish
wait ${PRODPID[*]}
# Normal exit
echo "All processes ended normal"
# kill timer
kill $TPID runtime=${1:-1m}
mypid=$
cp /Database/Client_db_200802110231.BAK .&
cpid=$!
sleep $runtime
kill -s SIGTERM $cpid
echo "Both processes are terminated".
# trap [commands] [traps]
trap "echo Booh!" SIGINT SIGTERM
aoeu aoeu
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