Commands by pooderbill (4)

  • Useful for finding newly added lines to a file, tail + can be used to show only the lines starting at some offset. A syslog scanner would look at the file for the first time, then record the end_of_file record number using wc -l. Later (hours, days), scan only at the lines that were added since the last scan. Show Sample Output


    1
    tail +### MYFILE
    pooderbill · 2015-04-23 11:49:15 0
  • view is the command: vi -r which opens a file in read-only mode. The + character jumps to the bottom of the logfile where the most relevant information starts. Other aliases can be created for commonly viewed logfiles. Show Sample Output


    -1
    view + LOGFILE
    pooderbill · 2015-04-21 11:23:01 2
  • ps and grep is a dangerous combination -- grep tries to match everything on each line (thus the all too common: grep -v grep hack). ps -C doesn't use grep, it uses the process table for an exact match. Thus, you'll get an accurate list with: ps -fC sh rather finding every process with sh somewhere on the line. Show Sample Output


    14
    ps -fC PROCESSNAME
    pooderbill · 2015-04-20 13:09:44 2
  • The shortest and most complete comment/blank line remover... Any line where the first non-whitespace character is # (ie, indented # comments), and all null and blank lines are removed. Use the alias as a filter: noc /etc/hosts or grep server /etc/hosts | noc Change to nawk depending awk versions. Show Sample Output


    1
    alias noc="awk 'NF && ! /^[[:space:]]*#/'"
    pooderbill · 2014-09-07 00:50:57 0

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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)

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"

How many days until the end of the year

Remove all leading and trailing spaces or tabs from all lines of a text file
Bash only, no sed, no awk. Multiple spaces/tabs if exists INSIDE the line will be preserved. Empty lines stay intact, except they will be cleaned from spaces and tabs if any available.

back ssh from firewalled hosts
host B (you) redirects a modem port (62220) to his local ssh. host A is a remote machine (the ones that issues the ssh cmd). once connected port 5497 is in listening mode on host B. host B just do a ssh 127.0.0.1 -p 5497 -l user and reaches the remote host'ssh. This can be used also for vnc and so on.

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"

Generate random IP addresses
It never ends

Replaces a color in a PDF document, useful for removing a dark background before printing.
The pdf is first converted to a bitmap, so change "-density" to match your printer resolution. Also be careful about the RAM required. In this example rgb(0,0,0) is replaced by rgb(255,255,255), change to suit your needs.

Print info about your real user.
To get your effective user: whoami


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