Bash and Command line One-Liners

From KCLUG Wiki

Jump to: navigation, search

This requires that you install the packages 'sharutils' and 'ImageMagick'. 

import -type Optimize -quality 100 -silent -window root png:- | uuencode ScreenShot.png | mail -s 'Taking a screenshot from the command line' billycrook@gmail.com

#!/bin/bash

#the machine to sync accounts to
sourcemachine=yourhost
for file in passwd shadow group gshadow
do
        scp ${sourcemachine}:/etc/${file} /etc/${file}.new
done


#list the db's and the from and too filenames
echo 'user /etc/passwd /etc/passwd.new
group /etc/group /etc/group.new' | \
while read object oldfile newfile
do
        #image the colons are spaces.  now get the name and old it number and iterate on each line
        sed 's/:/ /g' ${oldfile} | \
        while read name ignore oldid ignore2
        do
                #If the id number is between 500 and 65536 (If it's an actual person's user account)
                if [[ ${oldid} -ge 500 ]] && [[ ${oldid} -lt 65536 ]]
                then
                        unset newid

                        #find the correct new ID number
                        newid=$( grep "^${name}:x:" ${newfile} | sed -e "s/^${name}:x://" -e "s/:.*$//" )

                        #if newid not found, exit immediately and prompt admin
                        if [[ "${newid}" == "" ]]
                        then
                                echo "SEVERE ERROR: The ${object} ${name} was found in the old table, but not in the new table.  Add that ${object} on the source machine, and recopy etc/passwd,shadow,group,gshadow to this one."
                                exit 1
                        fi

                        #If there should be no change, save some work...
                        if [[ ${newid} -eq ${oldid} ]]
                        then
                                echo skipping ${object} ${name} because its id is ${oldid} in both tables.
                                continue
                        fi

                        #find an unused id number in that table, which is also unused in the goals file for that table
                        for try in `seq 500 65535`
                        do
                                #search for the id number in old new, and goals 
                                if ! grep -q ${try} ${oldfile} ${newfile} goals
                                then
                                        #once you've found one not in use, write it to goals
                                        echo ${object} ${oldid} ${try} ${newid} >> goals

                                        #print to secreen for debugging
                                        echo ${object} ${name} had oldid ${oldid}, and has newid ${newid}, will use ${try} as intermediary to get there.
                                        #exit the loop that's searching for unused ids
                                        break
                                fi
                        done

                fi      done
done

#go through toe goals list in two passes
for part in A B
do
        #in each pass, iterate over eachline, and pick out the object, oldid, intermediaryid, and newid
        cat goals | while read object oldid intermed newid
        do
                #in the first pass,
                if [[ ${part} == "A" ]]
                then
                        #add the action that takes the object to its intermediary ID
                        echo ${object} ${oldid} ${intermed} >> actions
                else    #in the second pass
                        #takle it to its destination id
                        echo ${object} ${intermed} ${newid} >> actions
                fi
        done
done

cat actions | while read object from to
do
        [[ ${object} == "group" ]] && prefix=':' || unset prefix
        echo chown --from=${prefix}${from} ${prefix}${to} -R / -c
done

#cleanup
rm goals  actions -f

#instate the new account tables
echo mv /etc/passwd /etc/passwd.orig
echo mv /etc/shadow /etc/shadow.orig
echo mv /etc/group /etc/group.orig
echo mv /etc/gshadow /etc/gshadow.orig

I like apg, and will probably still use it, but for scripts to be dependant on one less external binary, try this: 

pwchars="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"  ##add these on if you really want to be awnry \!\`~@#$%^&*(){}[]-_=+<,>.:;?/\\|"
pwlen=10
for (( c=1; c<=${pwlen}; c++ ))
do
        passwd="${passwd}${pwchars:$(($RANDOM%${#pwchars})):1}"
done
echo ${passwd}
Retrieved from "http://www.kclug.com/wiki/index.php/Bash_and_Command_line_One-Liners"
Personal tools