Commands using read sorted by votes

Commands using read (340)

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Download all images on a 4chan thread
This is sample output - yours may be different.
1

read -p "Please enter the 4chan url: "|egrep '//i.4cdn.org/[a-z0-9]+/src/([0-9]*).(jpg|png|gif)' - -o|nl -s https:|cut -c7-|uniq|wget -nc -i - --random-wait

unixmonkey73764 · 2014-03-09 05:56:14 6
Print one . instead of each line

this version only uses shell builtins
This is sample output - yours may be different.
1

alias ...='while read line; do echo -n "."; done && echo ""'

fpunktk · 2014-03-17 17:34:19 7
find which lines in a file are longer than N characters

Filter out lines of input that contain 72, or fewer, characters. This uses bash only. ${#i} is the number of characters in variable i. Show Sample Output
This is sample output - yours may be different.
```
$ ls /etc | while read i; do [ ${#i} -gt 72 ] && echo "$i"; done
-rw-r--r--.  1 root     root       4646 Mar  5 13:05 DIR_COLORS.lightbgcolor
-rw-r--r--.  1 root     root        863 Sep  2  2013 dleyna-renderer-service.conf
-rw-r--r--.  1 root     root        371 Mar  8 22:57 libguestfs-tools.conf
-rw-r--r--.  1 root     root       5122 Dec 24 06:57 makedumpfile.conf.sample
```
1

while read i; do [ ${#i} -gt 72 ] && echo "$i"; done < /path/to/file

flatcap · 2014-03-20 12:27:06 6
Get the gravatar UTL for a given email address
This is sample output - yours may be different.
1

echo -n test@example.com | md5sum | (read hash dash ; echo "https://secure.gravatar.com/avatar/${hash}")

kseistrup · 2014-04-20 08:56:59 8
Display the tree of all instance of a particular process
This is sample output - yours may be different.
1

pgrep 'sleep' | while read pid; do pstree -sa -H$pid $pid ; done

earthdan · 2014-04-29 08:47:32 6
Find 10 largest files in git history
This is sample output - yours may be different.
1

git verify-pack -v .git/objects/pack/pack-*.idx | grep blob | sort -k3nr | head | while read s x b x; do git rev-list --all --objects | grep $s | awk '{print "'"$b"'",$0;}'; done

qdrizh · 2014-06-25 07:37:24 6
RELINK a lot of broken symlinks - FIX broken symlinks after rsync site to new server

After you run this script, you can check status for broken symlink with this command: find -L . -type l
This is sample output - yours may be different.
1

find /PATHNAME -type l | while read nullsymlink ; do wrongpath=$(readlink "$nullsymlink") ; right=$(echo "$wrongpath" | sed s'|OLD_STRING|NEW_STRING|') ; ln -fs "$right" "$nullsymlink" ; done

iDudo · 2015-04-14 14:58:41 16
summarize a list of IP addresses, verifying IP address and giving counts for each IP found

Working with lists of IP addresses it is sometimes useful to summarize a count of how many times an IP address appears in the file. This example, summarizeIP, uses another function "verifyIP" previously defined in commandlinefu.com to ensure only valid IP addresses get counted. The summary list is presented in count order starting with highest count. Show Sample Output
This is sample output - yours may be different.
```
Example file containing a list of IPs:
$ nl list_of_IPs
     1  1.2.3.4
     2  5.6.7.8
     3  9.10.11.12
     4  13.14.15.16
     5  17.18.19.20
     6  21.22.23.24
     7  25.26.27.28
     8  some junk which should not be here
     9  29.30.31.32
    10  9.10.11.12
    11  9.10.11.12
    12  9.10.11.12
    13  1001.4.5.6

Having defined functions summaryIP and verifyIP (from previous commandlinefu.com posting):

$ summaryIP list_of_IPs
    4   9.10.11.12
    1   5.6.7.8
    1   29.30.31.32
    1   25.26.27.28
    1   21.22.23.24
    1   17.18.19.20
    1   13.14.15.16
    1   1.2.3.4
    
```
1

function summaryIP() { < $1 awk '{print $1}' | while read ip ; do verifyIP ${ip} && echo ${ip}; done | awk '{ip_array[$1]++} END { for (ip in ip_array) printf("%5d\t%s\n", ip_array[ip], ip)}' | sort -rn; }

mpb · 2015-05-01 16:45:05 10
list offsets from HEAD with git log.
This is sample output - yours may be different.
1

o=0; git log --oneline | while read l; do printf "%+9s %s\n" "HEAD~${o}" "$l"; o=$(($o+1)); done | less

bartonski · 2015-11-23 17:47:16 11
Get File Names from touch commands

retrieve file names back from touch commands for them Show Sample Output
This is sample output - yours may be different.
```
Input:
touch 01_intro.compressed.pdf; sleep 0.1;
touch 02_points.compressed.pdf; sleep 0.1;
touch 03_points.pdf; sleep 0.1;
touch lewis_pca_derivs.pdf; sleep 0.1;
touch shlens_pca.pdf; sleep 0.1;

Output:
01_intro.compressed.pdf
02_points.compressed.pdf
03_points.pdf
lewis_pca_derivs.pdf
shlens_pca.pdf
```
1

touch files.txt; cat reorder_files.sh | while read line; do x=`echo $line | sed 's/touch $[a-z0-9\.]\+.*.pdf$;.*/\1/'`; echo $x >> files.txt ; done;

programmer · 2016-04-19 11:01:17 12
Adding Prefix to File name

Adding course name prefix to lecture pdfs Show Sample Output
This is sample output - yours may be different.
```
Input:
10_simplify.pdf

Output:
CS749__10_simplify.pdf
```
1

ls *.pdf | while read file; do newfile="CS749__${file}"; mv "${file}" "${newfile}"; done;

programmer · 2016-04-19 11:04:47 16
Removing Prefix from File name

Removing Course name prefix added Show Sample Output
This is sample output - yours may be different.
```
Input:
CS749__10_simplify.pdf

Output:
10_simplify.pdf
```
1

ls *.pdf | while read file; do newfile="${file##CS749__}"; mv "${file}" "${newfile}"; done;

programmer · 2016-04-19 11:06:43 27
Create Bash script to change modification time of files

Create a bash script to change the modification time for each file in 'files.txt' such that they are in the same order as in 'files.txt' File name for bash script specified by variable, 'scriptName'. It is made an executable once writing into it has been completed. Show Sample Output
This is sample output - yours may be different.
```
Input:
01_intro.compressed.pdf
02_points.compressed.pdf
03_points.pdf

Output:
#!/bin/sh

touch 01_intro.compressed.pdf; sleep 0.5;
touch 02_points.compressed.pdf; sleep 0.5;
touch 03_points.pdf; sleep 0.5;
```
1

scriptName="reorder_files.sh"; echo -e '#!/bin/sh\n' > "${scriptName}"; cat files.txt | while read file; do echo "touch ${file}; sleep 0.5;" >> "${scriptName}"; done; chmod +x "${scriptName}";

programmer · 2016-04-19 11:52:00 15
cpu process limitation for specific processname like java,kibana

apt-get install cpulimit
This is sample output - yours may be different.
1

ps auxf | grep -v grep | grep -E -i "java|kibana" | awk {'print $2'} | while read pid; do cpulimit -l 25 -b -p $pid > /tmp/cpulimit_$pid ;done

aysadk · 2018-02-23 13:39:35 22
Process command output line by line in a while loop

This snippet allows to process the output of any bash command line by line.
This is sample output - yours may be different.
1

while read -r line; do echo $line; done < <(YOUR COMMAND HERE);

paulera · 2018-08-13 10:03:11 327
Alert visually until any key is pressed

I learned a few things reading this command. But I did run into a few issues: 1. On systems that don't use GNU echo (e.g. macOS 10.14.5 Mojave), the e option may not be supported. In this case ANSI escape codes will echoed as text and the terminal will not flash, like this: \e[?5h\e[38;5;1m A L E R T Thu Jun 20 16:31:29 PDT 2019 2. Since the read command strips\ignores leading backslashes, if a user types the backslash character once in the loop, it will not break. Typing backslash twice in a loop will break as expected. 3. The foreground color is set to red (\e[38;5;1m) on every loop. This could be set once before we call while, and then reset once when the loop breaks. 4. Instead of resetting the foreground color when it breaks, the video mode is set back to normal (\e[?5l). This has the effect of leaving the terminal text red until it is manually reset. The alternative I'm proposing here addresses these issues. I tested it on macOS and Arch Linux. Show Sample Output
This is sample output - yours may be different.
```
 A L E R T Thu Jun 20 16:31:29 PDT 2019
 A L E R T Thu Jun 20 16:31:30 PDT 2019
```
1

printf "\e[38;5;1m"; while true; do printf "\e[?5h A L E R T %s\n" "$(date)"; sleep 0.1; printf "\e[?5l"; read -r -s -n1 -t1 && printf "\e[39m" && break; done

z80a · 2019-06-21 00:05:16 37
Tail a log and replace according to a sed pattern

Tails a log and replaces it line-by-line according to whatever you want to replace. Useful if the file writing to the log can't be modified, so you need to modify its output instead. Show Sample Output
This is sample output - yours may be different.
```
echo "line1
find
line2" >> logfile

Output:
line1
replace
line2
```
1

tail -F logfile|while read l; do sed 's/find/replace/g' <<< $l; done

tyzbit · 2020-08-07 12:26:39 442
Batch-Convert text file containing youtube links to mp3
This is sample output - yours may be different.
1

cat playlist.txt | while read line; do youtube-dl --extract-audio --audio-format mp3 -o "%(title)s.%(ext)s" ytsearch:"$line" ;done

B4ckBOne · 2021-05-20 17:19:08 174
find packages installed from e.g. sid which are newer than those available from e.g. testing when sid is no longer present as a source repo

This is useful if you add sid, install some packages, then remove sid and want to work out which packages you installed from sid that should be removed (e.g. before an upgrade to the new stable). Alternatively you can think of this as "find installed packages that can no longer be installed."
This is sample output - yours may be different.
1

aptitude search -F '%p %v %V %O' '?narrow(?not(?archive("^[^n][^o].*$")),?version(CURRENT))' | while IFS=' ' read -r pkg ver candidate origin; do if [[ $ver == "$candidate" ]] && [[ $origin == '(installed locally)' ]]; then echo "$pkg"; fi; done

sorpigal · 2021-12-26 15:57:15 305
Customizable Search Context

customizable context searches - if you know sed, this is a basis for more complex context control than grep --context offers Show Sample Output
This is sample output - yours may be different.
```
$ echo -n search\>\  ; read SEARCH_STRING && sed -n "/$SEARCH_STRING/{n;p;n;p;n;p;q}" /etc/passwd
search> sshd
suse-ncc:x:105:107:Novell Customer Center User:/var/lib/YaST2/suse-ncc-fakehome:/bin/bash
uucp:x:10:14:Unix-to-Unix CoPy system:/etc/uucp:/bin/bash
uuidd:x:100:101:User for uuidd:/var/run/uuidd:/bin/false
```
0

echo -n search\>\ ; read SEARCH_STRING && sed -n "/$SEARCH_STRING/{n;p;n;p;n;p;q}" [file-to-search]

wwest4 · 2009-02-05 18:07:23 28
Search filenames with given pattern; each one is transfered via scp and if succesfull the file is locally deleted. Ideal for filesystem quick maintenance
This is sample output - yours may be different.
0

'ls -1 *<pattern>* | while read file; do scp $file user@host:/path/; if [[ $? -eq 0 ]]; then rm $file; fi; done'

perrefe · 2009-02-06 00:08:06 17
change to the selected directory for zsh users

Show Sample Output
This is sample output - yours may be different.
```
$ cd programs/
$ cd
$ scd 
0       ~
1       ~/programs
select number:
```
0

alias scd='dirs -v; echo -n "select number: "; read newdir; cd -"$newdir"'

aoiaoi · 2009-02-06 16:44:47 15
@mail.com by adding the line in list.txt

Add @mail.com each line of a list Show Sample Output
This is sample output - yours may be different.
```
$ while read line; do echo -e "$line@mail.com"; done < list.txt 
john@mail.com
mark@mail.com
white@mail.com
lion@mail.com
robert@mail.com
```
0

while read line; do echo -e "$line@mail.com"; done < list.txt

irraz · 2009-02-11 08:31:01 10
recursively change file name extensions

or, for a single directory: for f in *.c; do mv $f "`basename $f .c`".C; done Show Sample Output
This is sample output - yours may be different.
```
$ ls
kk1.c  kk2.c  kk3.c  kk4.c
$ find . -type f -name \*.c | while read f; do mv $f "`basename $f .c`".C; done
$ ls
kk1.C  kk2.C  kk3.C  kk4.C
```
0

find . -type f -name \*.c | while read f; do mv $f "`basename $f .c`".C; done

berta · 2009-02-17 09:30:43 10
Play a random .avi file from a media tree

unsets variables used by the one-liner sets up the IFS bash variable to not be affected by whitespace and disables extra glob expansion uses read to slurp the results of the find command into an array selects an element of the array at random to be passed as an argument to mplayer
This is sample output - yours may be different.
0

unset files i; set -f; O=$IFS; while IFS= read -r -d $'\0' files[i++]; do :; done < <(find . -name '*.avi' -print0) && IFS=$O; set +f && echo "Running: mplayer \"${files[ $(( $RANDOM % ${#files[@]} )) ]}\""

DEinspanjer · 2009-02-18 16:53:57 6
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Recursive find and replace file extension / suffix (mass rename files)

Find recursively all files in ~/Notes with the extension '.md' and pipe that via xargs to rename command, which will replace every '.md' to '.txt' in this example (existing files will not be overwritten).

extract audio from flv to mp3

list block devices

Shows all block devices in a tree with descruptions of what they are.

Change prompt to MS-DOS one (joke)

This one eliminates the additional backslash at the end (which is not necessary)

Chronometer in hour format

Shorter and faster...

Stream YouTube URL directly to mplayer.

This is the result of a several week venture without X. I found myself totally happy without X (and by extension without flash) and was able to do just about anything but watch YouTube videos... so this a the solution I came up with for that. I am sure this can be done better but this does indeed work... and tends to work far better than YouTube's ghetto proprietary flash player ;-) Replace $i with any YouTube ID you want and this will scrape the site for the _real_ URL to the full quality .FLV file on Youtube's server and will then will hand that over to mplayer (or vlc or whatever you want) to be streamed. In some browsers you can replace $i with just a % or put this in a shell script so all YouTube IDs can be handed directly off to your media player of choice for true streaming without the need for Flash or a downloader like clive. (I do however fully recommend clive if you wish to archive videos instead of streaming them) If any interest is shown I would be more than happy to provide similar commands for other sites. Most streaming flash players use similar logic to YouTube. Edit: 05/03/2011 - Updated line to work with current YouTube. It could be a lot prettier but I will probably follow up with another update when I figure out how to get rid of that pesky Grep. Sed should take that syntax... but it doesn't. Original (no longer working) command: mplayer -fs $(echo "http://youtube.com/get_video.php?$(curl -s $youtube_url | sed -n "/watch_fullscreen/s;.*$video_id.\+$&title.*;\1;p")")

Monitor all DNS queries seen by the local machine

[vim] Clear trailing whitespace in file

% acts on every line in the file. \s matches spaces. \+ matches one or more occurrences of what's right behind it. Character '$' matches end-of-line.

Update all packages installed via homebrew

As of March 7, 2012: $ brew update - downloads upgraded formulas $ brew upgrade [FORMULA...] - upgrades the specified formulas $ brew outdated - lists outdated installations Note updating all packages may take an excruciatingly long time. You might consider a discriminating approach: run `brew outdated` and select specific packages needing an upgrade. For more information see homebrew's git repository: https://github.com/mxcl/homebrew

Show the UUID of a filesystem or partition

Shows the UUID of a filesystem or partition that can be used in kernel root options and in fstab. Run it without the -u option to generate more information. eg: ~/ sudo vol_id /dev/sda2 ID_FS_USAGE=other ID_FS_TYPE=swap ID_FS_VERSION=2 ID_FS_UUID=27fca13d-97b7-4d28-882c-6d03353f0a82 ID_FS_UUID_ENC=27fca13d-97b7-4d28-882c-6d03353f0a82 ID_FS_LABEL= ID_FS_LABEL_ENC=

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Commands using read (340)

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