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Closed 8 years ago.
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Hello how to display the last sessions from all users connected to the system in linux (but that are not connected any more) ?
Using this last with awk:
last | awk 'NF>7 && !/still logged in/ && !seen[$1]++'
last -F | grep -v "still logged in" | cut -d " " -f1
The command for that is called last :-)
Please try below command:
last | awk 'NF>7 && !/still logged in/ && !seen[$1]++' | cut -d " " -f1
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Closed 1 year ago.
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I know what the commands ls and wc do, but I can not find out what ls > wc and ls | wc will show. Can someone please help me flush out the meaning of this commands?
ls | wc The output from the ls command is piped into the wc command. So it will count the words which are in the output of ls. So you see simply the number of files read by ls.
ls > wc This creates a new file in your current working directory with the name wc with the output of your ls command. The program wc is not used here, simply a new file with the same name is created. You can simply look into this new file with your favorite editor or simply use cat for it.
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Closed 3 years ago.
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I tail -f the log file of one of my services, but I would like to automatically stop my tail process once my logger has printed any content starting with OR containing ERROR or FATAL.
How can I achieve this?
To terminate tail -f immediately after the output has a line containing ERROR or FATAL, try:
tail -f file.log | awk '{print} /ERROR|FATAL/{exit}'
Example
$ cat file.log
abc
def
ghi
ERROR
jkl
mno
pqr
$ tail -f file.log | awk '{print} /ERROR|FATAL/{exit}'
abc
def
ghi
ERROR
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Closed 4 years ago.
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How to list only numerical directory names in Linux.
Only directories, that has only numeric characters?
There are multiple solutions to do it.
1.You can List just dirs and then remove . and / from the names and then Grep just numerical ones:
ls -d ./*/ | sed 's/\.\///g' | sed 's/\///g' | grep -E '^[0-9]+$'
2.By "ls" & "grep" & then "awk". Just list with details, Grep dirs and then Print 9th column:
ls -llh | grep '^d' | awk '{print $9}'
Good luck In Arbaeen.
In bash, you can benefit from extended globbing:
shopt -s extglob
ls -d +([0-9])/
Where
+(pattern-list)
Matches one or more occurrences of the given patterns
The / at the end limits the list to directories, and -d prevents ls from listing their contents.
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Closed 6 years ago.
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What is the equivalent of grep -e pattern1 -e pattern2 "$file" in Solaris?
In Linux it works fine. but in Solaris, i got "grep: illegal option -- e
Usage: grep -hblcnsviw pattern file . . ." error.
Can anyone help please?
Instead of:
# GNU grep only
grep -e pattern1 -e pattern2 file
...you can use:
# POSIX-compliant
grep -e 'pattern1
pattern2' file
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Closed 9 years ago.
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To count the number of files in a directory, I typically use
ls directory | wc -l
But is there another command that doesn't use wc ?
this is one:
ls -l . | egrep -c '^-'
Note:
ls -1 | wc -l
Which means:
ls: list files in dir
-1: (that's a ONE) only one entry per line. Change it to -1a if you want hidden files too
|: pipe output onto...
wc: "wordcount"
-l: count lines.