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Linux:Filters változata
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= Redirections =
<kivonat>>, >>, <</kivonat>
* Redirect the output of the ls command to the /tmp/lista-<username>.txt file, where the <username> is your login name! <megoldas>
<code lang="bash">
feri@columbo:~$ ls >/tmp/lista-feri.txt
</code>
Later it will be better solution:
<code lang="bash">
feri@columbo:~$ ls >/tmp/lista-${USER}.txt
</code></megoldas>
* Concatenate all files in the /etc directory which have .conf extension to one big file in named /tmp/lista-<username>.txt! What happened its previous content? <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/*.conf >/tmp/lista-feri.txt
</code>
A solution for later:
<code lang="bash">
feri@columbo:~$ cat /etc/*.conf >/tmp/lista-${USER}.txt
</code></megoldas>
* Append the current date and time to the end of the /tmp/lista-<username>.txt! <megoldas>
<code lang="bash">
feri@columbo:~$ date >>/tmp/lista-feri.txt
</code>
For later:
<code lang="bash">
feri@columbo:~$ date >>/tmp/lista-${USER}.txt
</code></megoldas>
* Create this new directory: /tmp! Redirect the error message into the hiba.txt! <megoldas>
<code lang="bash">
feri@columbo:~$ mkdir /tmp 2>hiba.txt
</code></megoldas>

= Filters =
<kivonat>grep, cut, wc, head, tail, tr, sort, uniq, tee, more (less, most), tac</kivonat>
* Show the content of /etc/passwd page by page!<megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | more
</code>

Another solution:
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | less
</code>

Another solution:
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | most
</code></megoldas>

* Show all lines from the /etc/passwd which contain the sh string! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep sh
</code></megoldas>
* Show all lines from the /etc/passwd which don't contain the sh string! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep -v sh
</code></megoldas>
* Show all lines from the /etc/passwd which first character is s! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep ^r
</code></megoldas>
* Show all lines from the /etc/passwd which last part is false! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep false$
</code></megoldas>
* Show all lines from the /etc/passwd which login name starts with f! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep ^f
</code></megoldas>
* Show all lines from the /etc/passwd which login name dont't contain feri! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | cut -d: -f1 | grep -v feri
</code></megoldas>
* Show all lines from the /etc/passwd which contains in the login name field the root user! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep ^root:
</code></megoldas>
* how many users are in that system whose name start with a vocal letter? Do not make difference between uppercase and lowercase letters! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep -i ^[aeiou]
</code></megoldas>
* How many user are there without a bash shell? <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep -v /bin/bash$
</code></megoldas>

* Show all lines from /etc/bash.bashrc which aren't comments and aren't empty! (Comments start with #, empty lines are ^$)! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/bash.bashrc | grep -v ^$ | grep -v ^'#'
</code></megoldas>
* Write the output of the previous task to your home directory into the bash.txt file! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/bash.bashrc | grep -v ^$ | grep -v ^'#' >bash.txt
</code></megoldas>
* How many folders are in the /etc which group right are: r-x? <megoldas>
<code lang="bash">
feri@columbo:~$ ls -l /etc | cut -c 5-7 | grep r-x | wc -l
</code></megoldas>
* Show the login history of the root (in this month)! <megoldas>
<code lang="bash">
feri@columbo:~$ last | grep root
</code></megoldas>
* Is the root user logged in the system? <megoldas>
<code lang="bash">
feri@columbo:~$ w | grep ^root
</code></megoldas>
* How many different shell exists in the system? <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | cut -d: -f7 | sort | uniq | wc -l
</code></megoldas>
* Show the name of all logged users! If somebody logged in more than once, only one name should be listed! <megoldas>
<code lang="bash">
feri@columbo:~$ w -h | cut -d' ' -f1 | sort | uniq
</code></megoldas>
* Which users has logged in this month except the reboot user?<megoldas>
<code lang="bash">
feri@columbo:~$ last | grep -v ^$ | grep -v 'wtmp begins' | cut -d' ' -f1 | sort | uniq | grep -v reboot
</code></megoldas>
* List the name of all users in a sorted list! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | cut -d: -f1 | sort
</code></megoldas>
* How many lines start in the /etc/passwd with f? <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | grep ^f | wc -l
</code></megoldas>
* Show the first three lines of the /etc/passwd file! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | head -3
</code></megoldas>
* Show the last seven lines of the /etc/passwd file! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | tail -7
</code></megoldas>
* Show the first twelwe and the last twelve names from the list of users! Try to solve this with one line! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | head -1 ; cat /etc/passwd | tail -12
</code></megoldas>
* Which user logged in first in this month? <megoldas>
<code lang="bash">
feri@columbo:~$ last | tail -3 | head -1
</code></megoldas>
* How many lines does have the /etc/passwd file? <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | wc -l
</code></megoldas>
* How many characters are in the /etc/passwd file last 8 lines? <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | tail -8 | wc -c
</code></megoldas>
* How many characters are in the directory of the /etc folder? <megoldas>
<code lang="bash">
feri@columbo:~$ ls /etc | wc -c
</code></megoldas>
* How many times has the root logged in this month? <megoldas>
<code lang="bash">
feri@columbo:~$ last | grep ^root | wc -l
</code></megoldas>
* show the sorted content of /etc/passwd! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | sort
</code></megoldas>
* Show all UIDs from the /etc/passwd in reverse order! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | cut -d: -f3 | sort -r -n
</code></megoldas>
* Which is the biggest UID in the /etc/passwd file? <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | cut -d: -f3 | sort | head -1
</code></megoldas>
* Show the first 15 lines in ascending order from the /etc/passwd! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | sort | head -15
</code></megoldas>
* How many lines and how many characters are in the output of the previous command? <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | sort | head -15 | wc -l -c
</code></megoldas>
* Show all real names from the /etc/passwd file and replace all spaces to a _ character! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | cut -d: -f5 | tr ' ' '_'
</code></megoldas>
* Delete all j character from the list of users! <megoldas>
<code lang="bash">
feri@columbo:~$ cat /etc/passwd | tr -d 'j'
</code></megoldas>
Vissza a(z) Linux:Filters laphoz.
A lap eredeti címe: „https://wiki.koczka.hu/index.php/Linux:Filters”
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