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Commands using cat from sorted by
Terminal - Commands using cat - 434 results
exec 5<>/dev/tcp/time.nist.gov/13; cat <&5 & cat >&5; exec 5>&-
2015-07-30 21:12:38
User: tyzbit
Functions: cat exec
Tags: bash Linux unix
14

Ever needed to test firewalls but didn't have netcat, telnet or even FTP?

Enter /dev/tcp, your new best friend. /dev/tcp/(hostname)/(port) is a bash builtin that bash can use to open connections to TCP and UDP ports.

This one-liner opens a connection on a port to a server and lets you read and write to it from the terminal.

How it works:

First, exec sets up a redirect for /dev/tcp/$server/$host to file descriptor 5.

Then, as per some excellent feedback from @flatcap, we launch a redirect from file descriptor 5 to STDOUT and send that to the background (which is what causes the PID to be printed when the commands are run), and then redirect STDIN to file descriptor 5 with the second cat.

Finally, when the second cat dies (the connection is closed), we clean up the file descriptor with 'exec 5>&-'.

It can be used to test FTP, HTTP, NTP, or can connect to netcat listening on a port (makes for a simple chat client!)

Replace /tcp/ with /udp/ to use UDP instead.

echo "text to prepend" | cat - file
cat <file>|column -t
for p in $(pgrep -t $(cat /sys/class/tty/tty0/active)); do d=$(awk -v RS='\0' -F= '$1=="DISPLAY" {print $2}' /proc/$p/environ 2>/dev/null); [[ -n $d ]] && break; done; echo $d
2015-05-18 20:01:20
User: geyslan
Functions: awk cat echo
Tags: display xorg
1

It's useful when you cannot access your env (systemd) or the process DISPLAY variable is not set. Perhaps also when you have a multi-head/user configuration.

diff <(ssh $remote_site cat $file) $file
2015-05-09 11:11:56
User: hal8
Functions: cat diff ssh
0

opens the output of some command as a file so this also works with graphical editors like meld, kdiff3 etc

meld <(ssh $remote_site cat .zshrc) .zshrc
a=$(b=$(($LINES/2));f() { for c in $(seq $b); do for i in $(seq $c);do echo x;done|xargs echo;done };paste <(f) <(f|tac|tr 'x' '-') <(f|tac|tr 'x' '-') <(f)|tr '\t' ' ');(cat <<<"$a"|tac;cat <<<"$a")|tr '-' ' '
for USER in /var/spool/cron/*; do echo "--- crontab for $USER ---"; cat "$USER"; done
2014-12-11 19:48:46
User: tyzbit
Functions: cat echo
0

This is not exhaustive but after checking /etc/cron* is a good way to see if there are any other jobs any users may have set.

Note: this is a repost from a comment "flatcap" made on http://www.commandlinefu.com/commands/view/3726/print-crontab-entries-for-all-the-users-that-actually-have-a-crontab#comment, for which I am grateful and I take no credit.

while sleep 1; do if [ $(echo "$(cat /proc/loadavg | cut -d' ' -f1) > .8 " | bc) -gt 0 ]; then echo -e "\n\a"$(date)" \e[5m"$(cat /proc/loadavg)"\e[0m"; ps aux --sort=-%cpu|head -n 5; fi; done
2014-12-08 15:44:40
User: tyzbit
Functions: cat echo head ps sleep
0

This checks the system load every second and if it's over a certain threshold (.8 in this example), it spits out the date, system loads and top 4 processes sorted by CPU.

Additionally, the \a in the first echo creates an audible bell.

cat File.txt | grep -io 'http://www.acme.com/a/files/.*.pdf'| uniq
cat /etc/named.conf | grep -Po '(?<=(named/)).*(?=\.db)'
2014-10-25 20:16:17
User: KonKar
Functions: cat grep
0

Allows you to have a list of the domains on the server.

cat /etc/httpd/logs/access.log | awk '{ print $6}' | sed -e 's/\[//' | awk -F'/' '{print $1}' | sort | uniq -c
2014-10-13 13:39:53
User: suyashjain
Functions: awk cat sed sort uniq
1

The command will read the apache log file and fetch the virtual host requested and the number of requests.

cat /usr/share/dict/words | egrep '^\w{13,}$' | egrep -iv '(\w).*\1'
2014-09-29 12:52:09
User: hackerb9
Functions: cat egrep
6

This is the most straightforward approach: first regexp limits dictionary file to words with thirteen or more characters, second regexp discards any words that have a letter repeated. (Bonus challenge: Try doing it in a single regexp!)

echo "DISK:";df -Pl | grep -v "Filesystem" | awk '{print $5,$6}' ; echo "MEM:" ; free -mto | awk '{ print $1,$2,$3,$4 }'; echo "CPU:"; top -b -d1 -n1 | grep Cpu | awk '{print $2,$3,$4,$5,$6,$7,$8,$9}';echo "LOAD:"; cat /proc/loadavg
2014-09-29 12:43:52
User: injez
Functions: awk cat df echo free grep top
0

Monitoring system in one line :

DISK : disk space

MEM: memory ( mem , swap, Total)

CPU : all information about cpu activity

LOAD : load average

cat /var/log/syslog | grep score= | awk '{print $15}' | more
w !sudo cat >%
cat h.txt| while read line; do curl -s -X POST 'https://www.virustotal.com/vtapi/v2/file/report' --form apikey="APIKEY" --form resource="$line"|awk -F'positives\":' '{print "VTHits"$2}'|awk -F' ' '{print $1" "$2$5$6}'|sed 's/["}]//g' && sleep 15; done
cat "log" | grep "text to grep" | awk '{print $1}' | sort -n | uniq -c | sort -rn | head -n 100
while true; do clear; cat /proc/[0-9]*/stat | cut -d' ' -f 3 | sort | uniq -c | awk '{print $2" "$1}'; echo '---'; sleep 1; done
$ wget --no-check-certificate -q checkip.dyndns.org -O index.html && cat index.html|cut -d ' ' -f 6 | cut -d '<' -f 1
2014-05-12 07:10:29
User: Superkikim
Functions: cat cut wget
0

This is the command line I use to get my IP address in order to update my zoneedit account. Full script on my blog http://akim.sissaoui.com/linux-attitude/script-de-mise-a-jour-ddns-zoneedit-com-en-bashsh/

cat ~/.ssh/id_rsa.pub | ssh deployer@xxxxx -p 52201 'cat >> ~/.ssh/authorized_keys'
for i in $(cat vulns.txt); do echo $i; rpm -qa ?changelog | grep -i $i; done
2014-04-30 16:11:14
User: sonny108
Functions: cat echo grep rpm
0

Found it online and could be very useful

cat dictionary.txt|while read a; do echo $a|cryptsetup luksOpen /dev/sda5 sda5 $a && echo KEY FOUND: $a; done
2014-04-16 18:49:53
User: rodolfoap
Functions: cat echo read
0

Lost your luks passphrase? You can always bruteforce from the command line. See the sample output, a simple command using a dictionary.

for i in {1..256};do p=" $i";echo -e "${p: -3} \\0$(($i/64*100+$i%64/8*10+$i%8))";done|cat -t|column -c120
2014-04-04 16:54:53
User: AskApache
Functions: cat column echo
6

Prints out an ascii chart using builtin bash! Then formats using cat -t and column.

The best part is:

echo -e "${p: -3} \\0$(( $i/64*100 + $i%64/8*10 + $i%8 ))";

From: http://www.askapache.com/linux/ascii-codes-and-reference.html

num_errs=`grep ERROR /var/log/syslog | tee >(cat >&2) | wc -l`
2014-03-12 00:04:24
Functions: cat tee wc
0

Many circumstances call for creating variable of a summary result while still printing the original pipe. Inserting "tee >(cat >&2)" allows the command output to still be printed while permitting the same output to be processed into a variable.

cat skype_log | sed -s 's/\(\[.*\]\) \(.*\): \(.*\)/<\2> \3/'