Linux Hints

  • Problem: Moving files into a web directory, even after changing permissions reporting a permission error when clicked on from web:
    • restorecon -r < path >
  • Adding a user to an existing group
    • usermod -a -G {group} (username}
  • Listing groups a user belongs to
    • groups {username}
  • Forcing all files in a folder to belong to a group:
    • chmod g+s dir
  • Ubuntu: setting your default shell:
    • chsh
    • then type the path to the shell you want, ex: /bin/bash
  • Adding a user
    • useradd -c "{USER FULL NAME}" -g {group} {username}
  • set password for a user
    • passwd {username}
  • Force the user to change their password on next login
    • chage -d 0 {username}
  • Copy disk image
    • sudo dd if=/path/of/source of=/path/of/destination bs=1M
  • Allow http/https through firewall
    • sudo firewall-cmd --add-service=http
    • sudo firewall-cmd --add-service=https
  • Write iso to bootable USB on openSUsE
    • Open SUSE Studio Imagewriter - run application


Kmail won't open folders

This one is mostly a matter of restarting so KMail can fetch those pesky items... Some possible steps: Use Alt + F2 or Konsole to type: kquitapp kmail, then wait a minute, then akonadictl stop, wait a minute, type akonadictl start, wait a minute, type kmail. This stops KMail (closing all windows), stops the KMail backend, starts the KMail backend, starts KMail. Having a working internet connection increases the chances of success. Sometimes, you can also just do kquitapp kmail, wait a minute, and start KMail again. Often, a few restarts seem to be needed. It is unclear what is the reason for this, but on bad network connections it is more likely to happen.


Merging PDF documents

gs -q -sPAPERSIZE=a4 -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=outputfile.pdf doc1.pdf doc2.pdf doc3.pdf ... docN.pdf

OpenSUSE disk issues

Snapper / btrfs

  • Configure /etc/snapper/configs/root to use say;
# limit for number cleanup

  • Use the following commands to see what is present and disk usage;
snapper list
btrfs fi usage /

  • Then manually run the cronjobs, if the system gets turned off sometimes they don't run...

qmail stored in /var/qmail/mailnames/

mail log /var/log/maillog


Topic revision: r12 - 2020-03-31 - TimMcDonald
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