Linux/Bash

cd ../home/catalyst/icdf

pwd (print working directory)

ls (list directory contents)

ls -alh (all, long listing format, human-readable)

ls -d */ (list directories only)

grep (globally search a regular expression and print)
$ grep apple fruitlist.txt
$ grep "mysqldump" .bash_history
$ grep PassivePortRange /etc/pure-ftpd.conf
grep -rnw 'directory' -e "pattern"
grep --include=\*.{php,config} -rnw 'directory' -e "pattern"
-r [recursive]
-n [line numbers]
-w [whole word match]

find
find /home/ -name horde.sql
find . -type f $ -name "*.class" -o -name "*.sh" $
find . -type f $ -name "configure.php" -o -name "configuration.php" $
http://www.hypexr.org/linux_find_help.php

To find the 10 most recently modified files, sorted in the reverse order of update time (most recent first):
find /some_dir -type f -printf '%TY-%Tm-%Td %TT %p\n' | sort -r | head -n 10

To search for files in /some_dir and all its sub-directories that have been modified in the last 2 days:
find /some_dir -type f -mtime -2 -printf '%TY-%Tm-%Td %TT %p\n'

Specify range. To search for files in /some_dir and all its sub-directories that have been modified in the last 7 days, but not in the last 3 days:
find /some_dir -type f -mtime -7 ! -mtime -3

find /some_dir -type f -mtime -7 ! -mtime -5 -printf '%TY-%Tm-%Td %TT %p\n'
OR (same result)
find /some_dir -type f -mtime +3 -mtime -7

To search for files in /some_dir (and all its sub-directories) that have been modified in the last 60 minutes, and print out their file attributes:
find /some_dir -type f -mmin -60 -exec ls -lah {} \;

Find files modified in the last 20 minutes:
find /tmp -type f -mmin -20 -exec ls -lah {} \;

Find files created in last 7 days:
find /tmp -type f -mtime -7 -ls
find /tmp -type f -mtime -7 -ls | wc -l

Find files belonging to user - last 10:

find /tmp -user bighornm -type f -ls | tail -10

Remove files belonging to user:
find /tmp -user xxxxxx -exec rm -fr {} \;

NOTE: "find" is a file locator while "grep" searches for patterns within a file.

cat (catenate - reads data from files and outputs contents)
cat file1.txt file2.txt

tac filename | less (read file backwards)

less filename
G - end of file
g - beginning of file
/ - search forward
? - search backward

cp (copy files and directories)

cp -R report/ reports/w\ (recursive)

chown (changes the owner and owning group of files)

chown root:root somefile

chown -R root:friends somefile (recursive)

chgrp (Changes group ownership of a file or files)

chgrp -R www-data reports/

chmod 744 ~/yada

chmod -R 744 ~/yada (-R = recursive)

User Group Other

r w x r w x r w x

4 2 1 4 2 1 4 2 1

COMMON PERMISSIONS:

-rw------- (600) — Only the owner has read and write permissions.

-rw-r--r-- (644) — Only the owner has read and write permissions; the group and others can read only.

-rwx------ (700) — Only the owner has read, write and execute permissions.

-rwxr-xr-x (755) — The owner has read, write and execute permissions; the group and others can only read and execute.

-rwx--x--x (711) — The owner has read, write and execute permissions; the group and others can only execute.

-rw-rw-rw- (666) — Everyone can read and write to the file. (Be careful with these permissions.)

-rwxrwxrwx (777) — Everyone can read, write and execute. (Again, this permissions setting can be hazardous.)

Here are some common settings for directories:

drwx------ (700) — Only the user can read, write in this directory.

drwxr-xr-x (755) — Everyone can read the directory, but its contents can only be changed by the user.

drwx--x--x (711) — cPanel user directories (/home/<username>

mysqldump xxxxxDBNAMExxxxx > xxxxxxxxxx.sql
mysql -u root xxxxxDBNAMExxxxx < databases/xxxxxxxxxx.sql
mysql database_name < database_name.sql

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Create an empty file:

touch filename.txt

Create a file with date string:

touch filename_"`date +"%Y_%m_%d"`".txt

mysqldump icdf | gzip > "/home/catalyst/DATA/icdf_db_"`date +"%Y_%m_%d"`".sql.gz"

"%" must be escaped in cron jobs:
mysqldump icdf | gzip > "/home/catalyst/DATA/icdf_db_"`date +"\%Y_\%m_\%d"`".sql.gz"

BUT - if backslashes added to ordinary command, they become part of the name (e.g. "icdf_db_TEST\2017_\08_\28.sql.gz")

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Vi Editor:
vi mytest.txt
- Type "i" to enter editing mode.
- Type text.
- Press "Esc" to return to command mode.
- Type ":wq" to save and close.

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Viewing, copying, moving and deleting files

ls ls -l	Display the contents of the current directory
ls -a ls -ltr ls -ld /lib/*/	Display also hidden files and hidden directories Order files by last modified date Directories only

cp filename /path/dir_name	Copy filename into directory /path/dir_name
cp -r dir_name /path/dir_name2	Copy the entire dir_name into /path/dir_name2
cp filename1 filename2 /path/dir_name	Copy filename1 and filename2 into /path/dir_name

rm name	Remove a file or directory called name
rm -r name	Remove an entire directory as well as its included files and subdirectories
rm -rf name	Remove an entire directory as well as its included files and subdirectories w/o prompts for all the files
find /home/modelsig/mail/new -type f -delete	Remove a ton of files to get around "too many arguments" problem
mv filename /path/dir_name	Move filename into /path/dir_name
mv filename1 filename2	Rename filename1 to filename2

cat filename	Display filenames contents

more filename	Display filename in pages. Use spacebar to view next page

less filename	Better than more
tac filename \| less	Read from end of file

head filename	Display filenames first 10 lines
head -15 filename	Display filenames first 15 lines

tail filename	Display filenames last 10 lines
tail -15 filename	Display filenames last 15 lines
tail -f myfile.txt	Outputs the last 10 lines of myfile.txt, and monitors myfile.txt for updates

pwd	Display current directory

cd /path/dir_name	Change to directory /path/dir_name
cd ..	Go 1 directory up

mkdir dir_name	Create directory dir_name
rmdir dir_name	Delete directory dir_name

Finding files and text within files

updatedb	Update (create first time used) a database of all files under the root directory /
locate filename locate crontab	Find file filename searching in the database All files that contain the word crontab

find / -name filename	Starting from the root directory search for the file called filename
find / -name *filename find -iname "MyCProgram.c" find -iname "MyCProgram.c" -exec md5sum {} \;	Same as above but search for file containing the string filename Case insensitive find Execute command on files found

grep string /path/dir_name grep -i "the" demo_file grep -A 3 -i "example" demo_text grep -r "ramesh" *	Starting from /path/dir_name search for all files containing string Case-insensitive Print matched line + 3 lines after Search for a given string in all files recursively

which application_name	Search $path for application app_name
whereis application_name	Search $path, man pages and source files for application_name

Archived files

Decompress

tar -xzf filename.tgz	Decompress tzg file
tar -xzf filename.tar.gz	Decompress tar.gz file
tar -xjf filename.tar.bz2	Decompress tar.bz2 file

Compress

tar -czf filename.tar /path/dir_name	Compress directory /path/dir_name to filename.tar
tar -czvf compressed_file.tar.gz file1.txt file2.jpg	Compress multiple files
gzip -c filename > filename.gz	Compress /path/dir_name to filename.tar.gz
bzip2 -c filename > filename.bz2	Compress /path/dir_name to filename.tar.bz2

Using rpm files

rpm -hiv package.rpm	Install rpm called package.rpm
rpm -hiv --force package.rpm	Install rpm called package.rpm by force
rpm -hUv package.rpm	Upgrade rpm called package.rpm
rpm -e package.rpm	Delete rpm called package.rpm
rpm -qpil package.rpm	List files in not-installed rpm called package.rpm
rpm -ql package.rpm	List files in installed rpm called package.rpm
rpm -q str	List installed rpms containing the string str
rpm -qf /path/application_name	Display the rpm that contains application application_name

Starting and Stopping

startx	Start the X system
shutdown -h now	Shutdown the system now and do not reboot
halt	Same as above
shutdown -r now	Reboot
reboot	Same as above
shutdown -r +10	Reboot in 10 minutes
shutdown -c	Cancel a pending shutdown
at 3:00 AM tomorrow at> echo "shutdown -r now" ENTER Control-D atq (to display the queue) atq 434 Fri Nov 9 15:25:00 2018 a root atrm deletes jobs, identified by their job number. atrm 434	Schedule a reboot using the at command. The at command schedules a command to be run once at a particular time that you normally have permission to run. The at command can be anything from a simple reminder message, to a complex script. You start by running the at command at the command line, passing it the scheduled time as the option. It then places you at a special prompt, where you can type in the command (or series of commands) to be run at the scheduled time. When you're done, press Control-D on a new line, and your command will be placed in the queue. $ at now + 1 minutes at> echo "Hello Fido" > test.txt at 9:30 PM Tue at noon at midnight at tomorrow (24 hrs. from now) at 2:30 PM tomorrow at 2:30 PM 10/21/2014
Restart Service	/etc/init.d/service restart /usr/local/cpanel/scripts/restartsrv service systemctl restart service-name.service ......... /etc/init.d/mysqld start /etc/init.d/mysqld stop /etc/init.d/mysqld restart service mysqld start service mysqld stop service mysqld restart service mysql start service mysql stop service mysql restart

Mounting filesystems

mount -t vfat /dev/sd(a)(1) /mnt/c_drive	Mount the first partition 1 of the first hard disk drive a which is in fat32 vfat dormat under /mnt/c_drive directory
mount -t iso9660 /dev/cdrom /mnt/cdrom	Mount cdrom under /mnt/cdrom directory

umount /mnt/hda1	Unmout the above

User administration

users	Display users currently logged in
adduser username	Create a new user called username
passwd username	Define password for user called username
who	List logged-in users
List users	`less /etc/passwd`
List users name only	`awk -F':' '{ print $1}' /etc/passwd`
who -b	Last reboot
last reboot	List of last reboots
last root	list of past logins for user "root"
whoami	Display current user
finger username	Displays info about user username
su	Log in as root from current login
su -	Log in as root from current login and take root's path
exit	Exit from console login (ie, logout).

Processes

command	Execute command in the foreground
command &	Execute command in the background
ctrl+z	Suspend a program
ctrl+c	Interrupt a program
ps	List all processes
kill -9 pid	Kill process with id pid
top	Monitor processes in real time

Networking

hostname	List the system's hostname
ifconfig	Set/Display network information
host ip	Resolves ip's hostname
ping ip/hostname	Check if ip/hostname is reachable
traceroute ip/hostname	Find network path to ip/hostname

System Information

uname -a	General system information
fdisk -l	List partition tables
cp filename /path/dir_name	Copy filename into directory /path/dir_name
df -T -h	List filesystem disk space usage
lspci	List PCI devices
lsusb	List USB devices
free -m	Display RAM+Swap usage

Program Compile

gcc -o output file.c	Compile a C program
./output	Run a C program you have compiled
g++ -o output file.cpp	Compile a C++ program
./output	Run a C++ program you have compiled
./configure && make && su -c 'make install'	Configure, compile and install a program with Makefile

CRONTABS

https://www.computerhope.com/unix/ucrontab.htm
https://www.cyberciti.biz/faq/how-do-i-add-jobs-to-cron-under-linux-or-unix-oses/
https://serverfault.com/questions/801257/should-i-edit-etc-crontab-or-run-crontab-e-as-root
https://www.thegeekstuff.com/2009/06/15-practical-crontab-examples

https://www.perl.com/article/43/2013/10/11/How-to-schedule-Perl-scripts-using-cron/

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When you create a crontab file, it is automatically placed in the /var/spool/cron/crontabs directory and is given your user name. You can create or edit a crontab file for another user, or root, if you have superuser privileges.

System crontabs: etc/crontab; etc/cron.daily; etc/cron.weekly; etc.

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LOAD CRONTAB FROM TEXT FILE:
crontab /home/catalyst/icdf/script/cron-file.txt

MAILTO=webmaster@wyoming.com
# First day of every month at 5am:
0 5 1 * * perl /home/catalyst/icdf/script/ContractExpireNotify.pl

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ROOT USER:
crontab -l

crontab -u michael.carroll -l
crontab /var/spool/cron/crontabs/www-data
sudo crontab -l -u jeff

Minute - Hour - Day - Month - Day(s) of Week

# Every minute:
* * * * * /home/catalyst/icdf/script/SendMailPerl.pl
# * * * * * /home/catalyst/icdf/script/ContractExpireNotify.pl
#
# Every 10 minutes:
# */10 * * * * /home/ramesh/check-disk-space
#
# Every day at 5am:
# 0 5 * * * /home/catalyst/icdf/script/ContractExpireNotify.pl
#
# Send the job output to a log file:
# 0 8 * * * /usr/local/bin/myjob > /var/log/myjob.log 2>&1

crontab -e
TO EXIT EDITOR:
:x<Enter> quit vi, writing out modified file to file named in original invocation
:wq<Enter> quit vi, writing out modified file to file named in original invocation
:q<Enter> quit (or exit) vi
:q!<Enter> quit vi even though latest changes have not been saved for this vi call

LIST USER CRONTABS:
ls /var/spool/cron

VIEW ALL CRONTABS:
more /etc/crontab

VIEW SINGLE USER CRONTAB:
crontab -u johnvinc -l

CRONTAB LOGS:
grep CRON /var/log/syslog
tail -10 /var/log/cron
cat /var/log/cron | grep johnvinc
head -10 /var/log/cron | grep johnvinc

REMOVE CRONTAB:
crontab -u johnvinc -r

RESTART CRON:
/etc/init.d/cron reload

Testing Cron Jobs By Simulating Cron Shell:
https://cronitor.io/docs/cron-troubleshooting-guide

# env -i /bin/sh
# cd ~
# env
PWD=/root

- Then run the script to see if there's a useful error message.

# /usr/local/bin/Libre_ap_report_mail.pl monthly
Can't locate Mail/Sender.pm in @INC (you may need to install the Mail::Sender module) (@INC contains: /etc/perl /usr/local/lib/x86_64-linux-gnu/perl/5.24.1 /usr/local/share/perl/5.24.1 /usr/lib/x86_64-linux-gnu/perl5/5.24 /usr/share/perl5 /usr/lib/x86_64-linux-gnu/perl/5.24 /usr/share/perl/5.24 /usr/local/lib/site_perl /usr/lib/x86_64-linux-gnu/perl-base) at /usr/local/bin/Libre_ap_report_mail.pl line 6.
BEGIN failed--compilation aborted at /usr/local/bin/Libre_ap_report_mail.pl line 6.

- Exit, then run # env again to see if there is something missing in the bare shell (/bin/sh).

- Might be able to do a fix on scripts like this:

use lib '/root/perl5/lib/perl5';

Give full access to user and group (i.e read, write and execute ) on a specific file.

$ chmod ug+rwx file.txt

Revoke all access for the group (i.e read, write and execute ) on a specific file.

$ chmod g-rwx file.txt

Apply the file permissions recursively to all the files in the sub-directories.

$ chmod -R ug+rwx file.txt

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LESS:

$ less huge-log-file.log

CTRL+F – forward one window

CTRL+B – backward one window

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$ mysql -u root -p

$ mysql -u root -pXXXXPWXXXXX

echo "Some Text..." > myfile.txt

echo "Some Text..." >> myfile.txt

q - to quit out of man page

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To view current processes:

ps aux | less

ps aux | grep "process-name"

ps aux | grep "httpd"

ps alx | grep "mysqld"

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Putty Text Colors:

* Executable files: Green
* Normal file : Normal
* Directory: Blue
* Symbolic link : Cyan
* Pipe: Yellow
* Socket: Magenta
* Block device driver: Bold yellow foreground, with black background
* Character device driver: Bold yellow foreground, with black background
* Orphaned syminks : Blinking Bold white with red background
* Missing links ( … and the files they point to) : Blinking Bold white with red background
* Archives or compressed : Red (.tar, .gz, .zip, .rpm)
* Image files : Magenta (.jpg, gif, bmp, png, tif)

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