cmdref.net is command references/cheat sheets/examples for system engineers.
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| Linux Commands Cheat Sheet popular | |
| bash | |
| OpenSSL popular | Check SSL Certificate Expiration Date : openssl s_client -connect example.com:443 </dev/null 2>/dev/null|openssl x509 -text|grep -E "Not|Issuer:|sha" |
| ssh popular | Create Key Pair : ssh-keygen -t rsa -C "comment" - How to use ProxyCommand with ssh - ssh portfoward |
| X11 Forwarding | |
| sudo | /etc/sudoers |
| su | /etc/pam.d/su |
| SELinux | /etc/selinux/config Check Command : getenforce |
| ntp | /etc/ntp.conf /etc/sysconfig/ntpd ntpdate -b -u IPADDRESS |
| cron | /var/spool/cron/USER /etc/cron.d/FILE |
| snmp | |
| LDAP | |
| PAM | |
| iptables |
| syslogd | (RHEL5/centos5) |
| rsyslog | (RHEL6,7/centos6,7) |
| journald | (RHE7/centos7) |
| syslog-ng | How to check Configuration:syslog-ng -s -f file |
| logrotate | /etc/logrotate.conflogrotate -d /etc/logrotate.d/httpd ← -d : test. don't lotate |
| tftp | Configuration : /etc/xinetd.d/tftp Check : tftp IPADDR |
| pxe | (preboot execution environment) |
| kickstart | |
| yum popular | |
| RHN (After RHEL5) | LANG=C rhn_register --nox --proxy=http://192.168.0.10:9999 |
Linux Network Configuration and Command
Linux Disk Configuration and Command
| Kernel Parameter | sysctl -a ← check /etc/sysctl.conf |
| User Resource | ulimit -a ← check /etc/security/limits.conf |