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===Bash stuff===

[[ShellScriptRegex Regular Expressions]]
[[BashGetOpt Options processing with getopt]]
-----

===Compiling shell scripts to binary executables===
http://www.datsi.fi.upm.es/~frosal/
Use the command **shc -f script_file_name**

===Bash===
CHeck out bash4 http://www.bash-hackers.org/wiki/doku.php/bash4


==Bash array and for loop==
%%
#!/bin/bash

DIRS[0]=one
DIRS[1]=two
DIRS[2]=three

for d in ${DIRS[@]}
do
echo $d
done
%%


==enable history timestamp==
Save this in /etc/bashrc, this will enable timestamp display with the history command

%%
export HISTTIMEFORMAT="%Y-%h-%d - %H:%M:%S "
%%

==bash shortcuts==
""<table border=1 class="data">
<tr><td>^a</td><td>Go to beginning of line</td></tr>
<tr><td>^a, alt-l</td><td>Go to beginning of line, and change all letters to lower case</td></tr>
<tr><td>alt-c</td><td>Change line to lower case</td></tr>
<tr><td>^e</td><td> Go to end of line</td></tr>
<tr><td>^r</td><td> Go to end of line</td></tr>
<tr><td>^k</td><td> Delete line</td></tr>
<tr><td>^w</td><td> Delete word</td></tr>
<tr><td>^y</td><td>Undo deletion</td></tr>
<tr><td>^l</td><td> Clear screen</td></tr>
</table>""

More at http://linuxhelp.blogspot.com/2005/08/bash-shell-shortcuts.html

==bash prompt==
Reference: http://tldp.org/HOWTO/Bash-Prompt-HOWTO/bash-prompt-escape-sequences.html
%%
PS1="\u@\h \W> "
%%

== Case switch ==
%%
case "$1" in
start)
do start;
;;

stop)
do stop;
;;

*)
echo usage;
;;
esac
%%

== Function and variables ==
%%
#!/bin/bash

function run() {
eval "$1=\"xxx\""
}

VAR=1
run VAR
echo $VAR
%%

%%
function myfunc()
{
local myresult='some value'
echo "$myresult"
}

result=$(myfunc)
echo $result
%%

== Compare floating point numbers ==
%%(bash)
#!/bin/bash
LOAD=`uptime | cut -d: -f5 | cut -d, -f1`
LIMIT=5.0
echo $LOAD
if [ `expr $LOAD \> $LIMIT` -eq 1 ]; then
# do your thing
fi
%%

== Read input, if then else ==
%%(bash)
echo "Please enter an address to forward to."
echo "To disable forward, type DISABLE. Default is null in 10seconds"
read -t10 fw
if [ $fw == "DISABLE" ];
then
echo "Disable mail forward done."
rm -Rf ~/.forward
elif [ $fw == "disable" ];
then
echo "Disable mail forward done."
rm -Rf ~/.forward
else
echo "Activating mail forward to $fw"
echo $fw > ~/.forward
fi
echo "Done."%%

==for loop ==
%%(bash)
TASKS=`ls -1 /scp/backup.jobs/*.sh`
for tt in $TASKS
do
eval $tt & LASTJOB=$!
wait $LASTJOB
done
%%

==if then else==
%%(bash)
if [ ! -f blah.txt ]; then
echo "File does not exist."
else
echo "File already exist."
fi
%%

== Text parsing ==
%%(bash)
sed -n "s/.*ok.*:.*:25 .*:\(.*\)::.*/\1/gp" /var/log/smtpd/current
cut -f5 -d: /var/log/smtpd/current | grep .
egrep -R ok /var/log/smtpd/current |awk '{print $6}'|sed -e 's/:/ /g'| cut -f2 -d' '
awk 'BEGIN {FS=":" } /ok/ {print $5}' /var/log/smtpd/current
fgrep ok /var/log/smtpd/current | cut -f5 -d: fgrep ok /var/log/smtpd/current | cut -f5 -d:
%%

== bash array and loops==
%%(bash)
#!/usr/local/bin/bash
PATH[0]=/home/sites/1/
PATH[1]=/home/sites/2/
PATH[2]=/home/sites/3/
PATH[3]=/home/sites/4/
PATH[4]=/home/sites/5/
arrsize=${#PATH[@]}
DATESTR=`/bin/date +%Y-%m`

for ((i=0;i<$arrsize;i++)); do
echo ${PATH[$i]}
find ${PATH[$i]} ! -name "*.zip" -mtime +31 | xargs zip -m ${PATH[$i]}/logs-$DATESTR.zip
done
exit 0
%%

==real example 1 ==
%%(bash)
#!/bin/bash
# script to get IP and MX record for a list of domains
# column definition
# COL1: domain name
# COL2: apache virtual host domain
# COL3: IP address of A record
# COL4: MX record(s)

function getip() {
IP=`host "$1" | awk '{print $4}' | sed s/found\:/NOT_FOUND/g`
if [ ${#IP} -lt 2 ]; then
# no record found
echo -n "NOT_FOUND"
else
echo -n $IP
fi
}

function getmx() {
MX=`host -tmx "$1" | grep handled | grep -v datapipe | awk '{print $7}' | sed '$!N;s/\n/\//g'`
if [ ${#MX} -lt 2 ]; then
# no MX record found
echo NONE
else
# get IP address for each MX record
MXIP=`host "$MX" | awk '{print $4}' | sed s/found\:/NOT_FOUND/g`
echo "$MX ($MXIP)"
fi
}

for f in `cat domains_step2.csv`
do
d=`echo $f | awk 'BEGIN {FS=","} {print $1}'`
echo -n $f
getip "$d"
echo -n ","
getmx "$d"
done
%%

===Parameter Expansion===
%%
JAVA_HOME=${JAVA_HOME:-"/usr/java/latest"}
%%

===Remove carriage returns===
%%
echo $text | tr -d '\n'
%%


===awk===
%%
awk -F: '($3 == "0") {print}' /etc/passwd
%%

===sed===
Inline editing
%%
sed -i.bak -e 's/Today/Yesterday/g' some_file.txt
%%