Common Commands:

 

Testing the success of failure of the last command.

test 34 -gt 23
echo $?
  0
test 34 -lt 23
echo $?
  1

Getting the process id, parent id and the command

ps -e -o pid,ppid,command

Backup currently dir contents to remote server 130.91.97.45, /home/user1/junk2/user1backup.tgz

tar zcvf - .| ssh user1@130.91.97.45 "cat > /home/user1/junk2/user1backup.tgz"

List only directories

find . -type d -maxdepth 1

or

ls -d */.

                       

Question:  Log files are created based on the amount of activity.  Some days, 4 to 7 log files may be created, other days no log files are created.  It's all based upon the amount of activity.

 

How is it possible to create a script that will delete all the logs that are >  3 days old.  However, if no log files have been written in the last several day, then, save the most recent 3, even if they are older than "n" days.   

 

 remove_old_log_files  

#!/bin/bash # # Only keep the most recent NUMLOGS log files # that haven't changed status the last n*24 hours # # The find command finds all '*.log' files # "-ctime +n" for files change status > n*24 # "-maxdepth 1" only search the current directory # "-type f" standard files # "-printf "%A@" returns seconds since Jan 1, 1970 # # Sort does just that ... sort # # awk gets count > NUMLOGS and prints # the name plus the path # User defined variables LOGFILE='*.c' NUMLOGS=2 CTIME='+3' # n*24 hours # # for i in `find . -ctime "${CTIME}" -type f -maxdepth 1 -name "${LOGFILE}" -printf "%A@ %p\n" 2>/dev/null|sort |awk 'NR > '"${NUMLOGS}"' {print $2}'` do echo $i; # Change echo to rm $i once you're convinced it works done

 

 

 

 

Find and Replace: Find and replace mchirico@med.upenn.edu with mchirico@users.sourceforge.net , assuming some of the files and or directories contain spaces.  Furthermore, don't replace if the file is under a CVS directory, contains a '~',or '#'.  Also, keep a log of all the replacements.  A special note, if the while read was used, the count variable would be created in a child process.  Thus, it would not get updated correctly in the final output.  Also, be careful when using continue statements as well. 

 

mreplace   #!/bin/bash # Copyright (C) 2003 Mike Chirico mmc mchirico@users.sourceforge.net GPL # Sample bash program to replace contents in files # # NoReplace_just_look=true # findstr='mchirico@med.upenn.edu' replacestr='mchirico@users.sourceforge.net' fileToListAllreplacements='/home/chirico/mreplace_log' # # find that ignores directory names; but, searches sub directories # ignore CVS directories and this filename mreplace # if [ -f $fileToListAllreplacements ] then echo "************" >> $fileToListAllreplacements echo `date` >> $fileToListAllreplacements fi count=0 #needed to handle tabs and spaces IFS=$'\n' # nothing in a CVS directory, or a file with ~ or # for i in `find . -name '*' -type f |grep -v 'CVS'|grep -v 'mreplace'| grep -v $fileToListAllreplacements | grep -v '~' | grep -v '#' ` # Don't use this: read commands in the shell create a new environment. Yes, it will work to find the files # but the count will be off because it will not be passed to the new environment. Also, becareful with a contiue statement as well #find . -name '*' -type f |grep -v 'CVS'|grep -v 'mreplace'| grep -v $fileToListAllreplacements | grep -v '~' | grep -v '#' | while read i # do if grep -q $findstr $i; then # uncomment to list what is relaced and the filename # grep -l $findstr $i|xargs -l1 awk '{print substr($0,0,30)}' >> $fileToListAllreplacements echo $i >> $fileToListAllreplacements if [ $NoReplace_just_look ] then echo $i else sed -e "s/$findstr/$replacestr/g" $i > $i.tmp && mv $i.tmp $i fi let count=$count+1 fi done if [ $NoReplace_just_look ] then echo "$count files found" else echo "$count replacements made" fi

 

Sample Program:

#!/bin/bash
# created mmc mchirico@users.sourceforge.net CopyRight 2003 GPL
# version 0.0.1b
#
# Creates a tar.gz file of all files after copying them
# into the $tarfile directory
# 
# If you want to auto-upload to sourceforge
# You'll need a .netrc with the following lines:
#      machine upload.sourceforge.net login anonymous password m@aol.com
# Then, if executed with a parameter ./myMakeTar 1
# will upload the file to sourceforge
#
#
tarfile="bashscripts.0.0.1b"
if [ -d $tarfile ]
then
  echo "Directory $tarfile exist" 
else
    mkdir $tarfile
fi
t=""
for i in `find .  -maxdepth 1 -iname '*' `
do
	case "$i" in
	"./CVS" ) continue;;
	"$0" ) continue;;
	*~ ) continue;;
	"./${tarfile}.tar.gz" ) continue;;    
	"./${tarfile}.tar" ) continue;;    
	"./${tarfile}" ) continue;;
	"./${tarfile:0:${#tarfile}-5}"* ) continue;;
	* ) t="${i} ${t}"; cp $i $tarfile/. ;;
	esac

done
tar -czf $tarfile".tar.gz" $tarfile

NOARGS=1
if [ -z $1 ]
then
    echo "  To upload file to sourceforge: `basename $0 ` 1"
    exit
else
# You'll need a ~.netrc with the following lines
# machine upload.sourceforge.net login anonymous password m@aol.com
    ftp << FTPSTRING
open upload.sourceforge.net 
cd incoming
put ${tarfile}.tar.gz
bye
FTPSTRING


fi

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diff and patch:  Useful for creating a patch to distribute to users.  Example below.

 

diff -c test1.c test2.c > test1_to_test2.patch

patch < test1_to_test2.patch

 

 

 

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More samples can be found in the download.