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Linux Foundation Certified SysAdmin (1) find (Case sensitive, find / …
Linux Foundation Certified SysAdmin
1) find
Case sensitive
find / -name "nome do arquivo"
find / -type c (character device)
find /etc -iname "teste.txt"
find /etc not -name "teste.txt"
find / -type l (links simbólicos)
find / -type d (directories)
find / -type -name "*.log"
find / -type d -name "log"
find /usr/bin -size +27000 (c - character, k - kilobytes, M - mega, G - giga
find / -type f -mtime 1 (list of files that was created one day ago
find / -user user
find /etc -user root | more
find /usr/bin -per 755
find / -name "test.txt" -exec chmod 700 {} \;
2) wich
wich python
which ifconfig
3) locate test.txt, updatedb
4) File System
Journaling
Prevent data corruption
Ext - Extended File System - Introduced in 1992
Ext2 - Was the first file system to support extended file attributes (x-attrs) and 2TB+ drives
Ext3 - Introduced journaling
Ext4 - designed to be backward compatible and introduced some additional features
BtrFS
Designed by Oracle
B-Tree File System
Drive pooling
snapshots
compression
online defragmentation
Same ideas of ReiserFS
ReiserFS
Introduced in 2001
small text files
ZFS
SUN, acquired by Oracle
Drive pooling, snapshots, dynamic disk striping
Each file has a checksum
Uses it for containers by default
XFS
Ported in Linux in 2001
Similar to Ext4
Can be enlarged (but not shrunk) on the fly
Good with large files (like backup servers)
Poor with many small files (like web servers)
JFS
Journaled File System
Developed by IBM
Low CPU usage
Good performance regardless of file size
Partitions can be dynamically enlarged but not shrunk
Support in mos every major distribution
Not as widely tested in production as Ext4
5 - Commands
cat
cat arq.txt |more
sort
sort -r arq.txt |more
fmt, format text, ex: fmt -u format.txt
nl
cut -d ";" -f1 delimited.txt
6) Boot, reboot, shuting down
w - who is logged in
shutdown -r now
uptime
shutdown -h +5m, now
7) Boot or change system into different operating modes
System V Runlevels
7 Runlevels
0 - halt
6 - reboot
1 - Single user mode
2 - Multi user mode without networking
3 - Multi user with networking
5 - Multiuser with x window and networking
runlvel
See what runlevel
Systemd
8) Caching DNS Server
Basically designed to query DNS Servers
Later use
Reduce response time
yum install bind bind-utils
named-checkconf /etc/named.conf