Differences

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--- linux:ubuntu:useful-commands [2024/02/08 02:44] – [[ip] Show routing table / find default gateway] odefta
+++ linux:ubuntu:useful-commands [2024/02/08 17:12] (current) – [[user] Change mode] odefta
@@ Line 4: / Line 4: @@
 <code>
 file file.txt
+</code>
+===== [cat] Add line numbers to a file =====
+<code>
+cat -n file.txt
+nl file.txt
 </code>
@@ Line 260: / Line 266: @@
 <code>
 sudo ip link show
+</code>
+===== [ip] UP / DOWN states of network interfaces =====
+Display only the names and states (UP / DOWN) of the network interfaces on the system, using the format interface_name:state.
+<code>
+ip link show | awk '/^[0-9]+:/ {print $2 " " $9}' | sed 's/://g' | awk '{print $1 ":" ($2=="UP"?"UP":"DOWN")}'
+</code>
+Output:
+<code>
+lo:DOWN
+ens33:UP
+ens34:UP
+docker0:DOWN
+br1:DOWN
+br2:DOWN
 </code>
@@ Line 285: / Line 308: @@
 ping -c 4 10.125.50.50
 </code>
-c - number of packets to send (by default in infinite)
+c - number of packets to send (by default is infinite)
 ===== [ip] Show routing table / find default gateway =====
@@ Line 482: / Line 505: @@
 grep -o 'searched_string' file.txt | wc -l
 </code>
-o - print each occurrence on a separate line
+o - print each occurrence on a separate line \\
 l (from wc) - count lines
@@ Line 495: / Line 518: @@
 grep -nri search workspace/C/ | less
 </code>
-n - show line number
+n - show line number \\
-r - recursive
+r - recursive \\
 i - case insensitive
@@ Line 736: / Line 759: @@
 ls [abc]*.txt
 </code>
-[abc] - characters a, b or c
+[abc] - characters a, b or c \\
-* - any number of characters (including 0)
+* - any number of characters (including 0) \\
 .txt - ends with txt
@@ Line 1057: / Line 1080: @@
 echo -e "5\n3\n8\n1" | sort -n
 </code>
-e - interpret escape sequences
+e - interpret escape sequences \\
 n - numbers (sort as numbers)
@@ Line 1172: / Line 1195: @@
 <code>
 history | awk '{$1=""; print $0}' | sort | uniq -c | sort -nr -k1 | head -10 | awk '{$1=""; print $0}'
+</code>
+===== [for] Start 10 processes in background then kill them =====
+<code>
+for i in {1..10}; do sleep 3000 & done; pkill sleep
+</code>
+===== [for] Create 15 files - their names contains numbers =====
+Using a one-liner, create 15 files with names ranging from final-exam-00.txt to final-exam-15.txt.
+<code>
+for i in {0..15}; do touch final-exam-$(printf "%02d" $i).txt; done
 </code>
@@ Line 1487: / Line 1524: @@
 </code>
 {{:linux:ubuntu:pasted:20240208-023728.png}}
+===== [bash] [ps] Script to display every second the process with highest CPU usage =====
+<code bash top.sh>
+#!/bin/bash
+while true; do
+    clear
+    #echo "Update on: $(date)"
+    echo "Process with highest CPU usage:"
+    ps -eo %cpu,pid,command --sort=-%cpu | head -n 2
+    sleep 1
+done
+</code>
+{{:linux:ubuntu:pasted:20240208-030524.png}}
 ===== [git] Configure initial settings =====
@@ Line 1723: / Line 1775: @@
 <code>
 w | awk 'FNR>2 {print $1}'
+</code>
+===== [user] Display the users who have opened a terminal on the host system =====
+<code>
+who | awk '$2 ~ /^tty/ {print $1}'
+</code>
+<code>
+~ - equals for regular expressions
+/ / - delimitates a regular expression
+^tty - starts with tty.
 </code>
@@ Line 1892: / Line 1956: @@
 </code>
-Eliminare read permission for group:
+Eliminate read permission for group:
 <code>
 chmod 601 file.txt
@@ Line 1898: / Line 1962: @@
 </code>
-Eliminare write permission for all:
+Eliminate write permission for all:
 <code>
 chmod ugo-w file.txt