Commands by maher (2)

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display a smiling smiley if the command succeeded and a sad smiley if the command failed
you could save the code between if and fi to a shell script named smiley.sh with the first argument as and then do a smiley.sh to see if the command succeeded. a bit needless but who cares ;)

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Btrfs: Find file names with checksum errors
Btrfs reports the inode numbers of files with failed checksums. Use `find` to lookup the file names of those inodes. The files may need to be deleted and replaced with backups.

Save your open windows to a file so they can be opened after you restart
This will save your open windows to a file (~/.windows). To start those applications: $ cat ~/.windows | while read line; do $line &; done Should work on any EWMH/NetWM compatible X Window Manager. If you use DWM or another Window Manager not using EWMH or NetWM try this: $ xwininfo -root -children | grep '^ ' | grep -v children | grep -v '' | sed -n 's/^ *\(0x[0-9a-f]*\) .*/\1/p' | uniq | while read line; do xprop -id $line _NET_WM_PID | sed -n 's/.* = \([0-9]*\)$/\1/p'; done | uniq -u | grep -v '^$' | while read line; do ps -o cmd= $line; done > ~/.windows

Find ulimit values of currently running process
When dealing with system resource limits like max number of processes and open files per user, it can be hard to tell exactly what's happening. The /etc/security/limits.conf file defines the ceiling for the values, but not what they currently are, while $ ulimit -a will show you the current values for your shell, and you can set them for new logins in /etc/profile and/or ~/.bashrc with a command like: $ ulimit -S -n 100000 >/dev/null 2>&1 But with the variability in when those files get read (login vs any shell startup, interactive vs non-interactive) it can be difficult to know for sure what values apply to processes that are currently running, like database or app servers. Just find the PID via "ps aux | grep programname", then look at that PID's "limits" file in /proc. Then you'll know for sure what actually applies to that process.

Which processes are listening on a specific port (e.g. port 80)
swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Convert seconds to [DD:][HH:]MM:SS
Converts any number of seconds into days, hours, minutes and seconds. sec2dhms() { declare -i SS="$1" D=$(( SS / 86400 )) H=$(( SS % 86400 / 3600 )) M=$(( SS % 3600 / 60 )) S=$(( SS % 60 )) [ "$D" -gt 0 ] && echo -n "${D}:" [ "$H" -gt 0 ] && printf "%02g:" "$H" printf "%02g:%02g\n" "$M" "$S" }

Create a mirror of a local folder, on a remote server
Create a exact mirror of the local folder "/root/files", on remote server 'remote_server' using SSH command (listening on port 22) (all files & folders on destination server/folder will be deleted)

Directory Tree

Ping all hosts on 192.168.1.0/24


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