Изменить / dev / sd * для установки USB Linux?

Так много вариантов, выберите тот, который вам нравится.

Использование grep:

grep -o '^[^:]\+:[^:]\+' file.txt

использование cut:

cut -d: -f1-2 file.txt

using awk:

awk -F: '{ print $1$2 }' file.txt

using sed:

sed 's/^\([^:]\+:[^:]\+\).*/\1/' file.txt

using shell:

while IFS=: read -r i j k; do echo "$i$j"; done <file.txt

using perl:

perl -pe 's/^([^:]+:[^:]+).*/$1/' file.txt

Пример:

$ grep -o '^[^:]\+:[^:]\+' file.txt
student1234 "GET https://www.noname.com
student4567 "GET http:// www.noip.edu
student8901 "GET http:// www.testing.org

$ cut -d: -f1-2 file.txt                                                
student1234 "GET https://www.noname.com
student4567 "GET http:// www.noip.edu
student8901 "GET http:// www.testing.org

$ awk -F: '{ print $1$2 }' file.txt                 
student1234 "GET https//www.noname.com
student4567 "GET http// www.noip.edu
student8901 "GET http// www.testing.org

$ sed 's/^\([^:]\+:[^:]\+\).*/\1/' file.txt            
student1234 "GET https://www.noname.com
student4567 "GET http:// www.noip.edu
student8901 "GET http:// www.testing.org

$ while IFS=: read -r i j k; do echo "$i$j"; done <file.txt
student1234 "GET https//www.noname.com
student4567 "GET http// www.noip.edu
student8901 "GET http// www.testing.org

$ perl -pe 's/^([^:]+:[^:]+).*/$1/' file.txt
student1234 "GET https://www.noname.com
student4567 "GET http:// www.noip.edu
student8901 "GET http:// www.testing.org