I'd like to be able to tail the output of a server log file that has messages like:
INFO
SEVERE
etc, and if it's SEVERE, show the line in red; if it's INFO, in green. What kind of alias can I setup for a tail command that would help me do this?
Try out multitail¹. This is an übergeneralization of tail -f. You can watch multiple files in separate windows, highlight lines based on their content, and more.
multitail -c /path/to/log
The colors are configurable. If the default color scheme doesn't work for you, write your own in the config file. For example, call multitail -cS amir_log /path/to/log with the following ~/.multitailrc:
colorscheme:amir_log
cs_re:green:INFO
cs_re:red:SEVERE
Another solution, if you're on a server where it's inconvenient to install non-standard tools, is to combine tail -f with sed or awk to add color selection control sequences. This requires tail -f to flush its standard output without delay even when its standard output is a pipe, I don't know if all implementations do this.
tail -f /path/to/log | awk '
/INFO/ {print "\033[32m" $0 "\033[39m"}
/SEVERE/ {print "\033[31m" $0 "\033[39m"}
'
or with sed
tail -f /path/to/log | sed --unbuffered \
-e 's/\(.*INFO.*\)/\o033[32m\1\o033[39m/' \
-e 's/\(.*SEVERE.*\)/\o033[31m\1\o033[39m/'
If your sed isn't GNU sed, replace \o033 by a literal escape character and remove --unbuffered.
Yet another possibility is to run tail -f in an Emacs shell buffer and use Emacs's syntax coloring abilities.
¹ The historical website vanished in early 2021. The latest version is still available in many distributions, e.g. Arch, Debian.
sed? (sorry for being lazy and not figuring it out myself!) But would you please add a sed example as well.
– Ali
Nov 28 '11 at 16:41
tail -f with awk code, if a string doesn't have INFO and SEVERE, the string isn't be printed. How can I print the remain strings either? (The string doesn't need to be colored)
– Benjamin
Jun 29 '12 at 10:32
; next before the closing braces to skip further processing, and a new processing line 1 {print} at the end (1 means always).
– Gilles 'SO- stop being evil'
Jun 29 '12 at 11:58
sed, the problem is that it uses buffer, so I don't see the content appearing until the buffer is full. I've added --unbuffered.
– Ondra Žižka
Dec 07 '17 at 14:41
sed --unbuffered -e 's/\(.*FATAL.*\)/\o033[1;31m\1\o033[0;39m/' -e 's/\(.*ERROR.*\)/\o033[31m\1\o033[39m/' -e 's/\(.*WARN.*\)/\o033[33m\1\o033[39m/' -e 's/\(.*INFO.*\)/\o033[32m\1\o033[39m/' -e 's/\(.*DEBUG.*\)/\o033[34m\1\o033[39m/' -e 's/\(.*TRACE.*\)/\o033[30m\1\o033[39m/' -e 's/\(.*[Ee]xception.*\)/\o033[1;39m\1\o033[0;39m/'
– DmitrySandalov
Sep 07 '18 at 15:07
sed doesn't accept --unbuffered. Nor does it accept \oNNN sequences. For the latter, I had to use embedded printfs like here
– Kelvin
Apr 10 '19 at 21:52
multitail no longer works, and the site no longer maintains a valid certificate.
– ndemarco
May 27 '21 at 14:30
tail -f /some/log | awk '/INFO/ {print "\033[32m" $0 "\033[39m"; next} 1{print}'
– thebarless
Jan 04 '23 at 12:39
Have you had a look at ccze? You have the possibility to customize the default colors of some keywords using the option -c or directly in your configuration file. If your screen is clearing after colorizing you must use option -A.
Edit:
If you really would like to have the complete line colored in red, you could also have a try at the following:
$ tail -f myfile.log | perl -pe 's/.*SEVERE.*/\e[1;31m$&\e[0m/g'
\e[1;31m will give you the red color. If you would like some yellow, use \e[1;33m, and for green use \e[1;32m. The \e[0m restores the normal text color.
\007 to the end of the regex, like so: perl -pe 's/(ERROR)/\033[31m$1\033[0m\007/g;'. This works awesome if you are using tmux with set -g bell-action any, in which case if you have your log tailing in another window, that window name will alert whenever the regex finds a match.
– J.C. Yamokoski
Nov 13 '12 at 04:15
ccze running for several days it will eventually hang and all output will be buffered and not printed to the screen. Really frustrating and makes it unusable.
–
Nov 30 '14 at 12:46
grep $1 | perl -pe 's/'$1'/\e[1;31m$&\e[0m/g' in my script...
– Betlista
Aug 10 '17 at 09:47
brew install ccze and the result works: tail -f -n 500 /private/var/log/system.log | ccze
– jerclarke
Jun 27 '18 at 17:50
Have a look at lnav, the advanced log file viewer.
It can also pretty print various formats.
Before:
After:
select log_time, log_level, log_body from syslog_log where log_body like '%CPU%'
– campisano
Aug 29 '20 at 17:49
You can use rainbow, which colorizes lines based on regular expressions:
rainbow --red='SEVERE.*' --green='INFO.*' tail -f my-file.log
It also comes bundled with predefined configs, for example for Tomcat logs:
rainbow --config=tomcat tail -f my-file.log
(disclaimer: I am the author)
tail -f. Particularly rainbow --red=CRITICAL tail -f var/log/dev.log works perfect but tail -f var/log/dev.log | rainbow --red=CRITICAL does the bug. Should I open an issue in github?
– Xavi Montero
Jan 02 '23 at 11:37
You can use colortail:
colortail -f /var/log/messages
Unfortunately there is no way to set bold or other colors like orange.
– lepe Jan 27 '14 at 03:55apt install colortail and it should work without editing ~/.colortail/ too.
– Kartik M
May 06 '19 at 12:05
Also note that if you just want to look for one matching regex, GNU grep with --color will work — just pipe your tail output through that.
grep -A9999 -B9999 regex, it will show all lines unless you have 10,000 non-matching lines in a row. Use something like GREP_COLORS="ms=31:sl=33:cx=32" grep -A9999 -B9999 SEVERE to show the word SEVERE in red, the rest of SEVERE lines in yellow, and all other (non-SEVERE) lines (up to 9999) in green.
– G-Man Says 'Reinstate Monica'
Aug 07 '15 at 02:45
--color=always to grep instead of just --color, depending on the order of your pipe, but yes, this works tail (GNU coreutils) 8.27 installed on my box.
– Hannah Schultz
Jul 02 '18 at 15:26
To get colored output from standard commands like grep, you should set this alias in your .bashrc
# User specific aliases and functions
alias grep='grep --color=auto'
when you grep something in your file you see something like this, (but probably in red):
[root@linuxbox mydir]# grep "\(INFO\|SEVERE\)" /var/log/logname this entry is an INFO SEVERE this entry is a warn! this entry is an INFO this entry is an INFO SEVERE this entry is a warn!
if want to use tail or awk and want that the color survive to a pipe, then the alias is not enough and you should use the --color=always parameter, for example:
[root@linubox mydir]# grep --color=always "\(INFO\|SEVERE\)" /var/log/logname | tail -f | awk '{ print $1 }'
this
SEVERE
this
this
SEVERE
If you want color text with awk the story is a little bit complex but more powerfull, for example:
[root@linubox mydir]# tail -f /var/log/messages | awk '{if ($5 ~ /INFO/) print "\033[1;32m"$0"\033[0m"; else if ($1 ~ /SEVERE/) print "\033[1;31m"$0"\033[0m"; else print $0}'
this entry is an INFO
SEVERE this entry is a warn!
this is another ENTRY
this entry is an INFO
this is another ENTRY
this entry is an INFO
SEVERE this entry is a warn!
with each line in its own color.
There are many other way to get colorized text from shell with other tools and they are well descripted by other members.
I quite like colorex. Simple, yet satisfying.
tail -f /var/log/syslog | colorex -G '[0-9]{2}:[0-9]{2}:[0-9]{2}' -b $(hostname)
Based on @uloBasEI answer, I've tried to use ... | perl ... | perl ..., but Linux pipe gets a bit crazy and is too slow. If I put all rules in only one perl command, it works fine.
For example, create a perl file colorTail.pl as below:
#!/usr/bin/perl -w
while(<STDIN>) {
my $line = $_;
chomp($line);
for($line){
s/==>.*<==/\e[1;44m$&\e[0m/gi; #tail multiples files name in blue background
s/.*exception.*|at .*/\e[0;31m$&\e[0m/gi; #java errors & stacktraces in red
s/info.*/\e[1;32m$&\e[0m/gi; #info replacement in green
s/warning.*/\e[1;33m$&\e[0m/gi; #warning replacement in yellow
}
print $line, "\n";
}
Use it as:
tail -f *.log | perl colorTail.pl
tail -f *.log -f **/*.log | perl colorTail.pl
NOTE: you can use it on MobaXTerm too! Just download perl plug-in from MobaXTerm site.
tail -f /var/log/logname | source-highlight -f esc -s log
source-highlight isn't a widely installed command, so you should at least give a link to the project site.
– Gilles 'SO- stop being evil'
Mar 16 '11 at 22:45
One solution that works for coloring all sorts of text, not just logfiles, is a Python tool, 'colout'.
pip install colout
myprocess | colout REGEX_WITH_GROUPS color1,color2... [attr1,attr2...]
Where any text in the output of 'myprocess' which matches group 1 of the regex will be colored with color1, group 2 with color2, etc.
For example:
tail -f /var/log/mylogfile | colout '^(\w+ \d+ [\d:]+)|(\w+\.py:\d+ .+\(\)): (.+)$' white,black,cyan bold,bold,normal
i.e. the first regex group (parens) matches the initial date in the logfile, the second group matches a python filename, line number and function name, and the third group matches the log message that comes after that. This looks like:
Note that lines or parts of lines which don't match any of my regex are still echoed, so this isn't like 'grep --color' - nothing is filtered out of the output.
Obviously this is flexible enough that you can use it with any process, not just tailing logfiles. I usually just whip up a new regex on the fly any time I want to colorize something. For this reason, I prefer colout to any custom logfile-coloring tool, because I only need to learn one tool, regardless of what I'm coloring: logging, test output, syntax highlighting snippets of code in the terminal, etc.
As for the color codes, I would use tput:
red=$( tput -Txterm setaf 1 )
norm=$( tput -Txterm sgr0 )
bold=$( tput -Txterm bold )
See for reference: man tput
Then:
tail -F myfile.log | sed "s/\(.ERROR.*\)/$red$bold\1$norm/g"
grc for sure!
customize your collors with regex in the file: ~.grc/conf.tail (or whatever name you want)
regexp=.*(select .*)$
colours=unchanged,cyan
=====
regexp=.*(update .*)$
colours=unchanged,bold yellow
=====
regexp=.*(insert .*)$
colours=unchanged,bold yellow
=====
regexp=.*(emp=\d+).*
colours=unchanged,reverse green
=====
regexp=.*http.*/rest/contahub.cmds.(.*?)/(\w*).*$
colours=unchanged,green,magenta
=====
regexp=.*http.*/M/.*\.(.*?Facade)/(\w*).*$
colours=unchanged,underline green,underline magenta
command line:
grc -c conf.tail tail -f log/tomcat/catalina.out
results:
info for configuring grc: https://github.com/manjuraj/config/blob/master/.grc/sample.conf
Shameless plug: I wrote a tool called TxtStyle that does something similar as the options mentioned earlier. You can run it as follows:
tail -f /var/log/syslog | txts --regex '\d+'
You can also define named styles in the config file (~/.txts.conf) and use it like so:
ifconfig | txts --name ifconfig
(ifconfig style is defined out of the box)
You might also want to take a look at lwatch:
tail -f /var/log/syslog | lwatch --input -
I wrote a bash function that accepts up to three parameters and does a grep-like filter on a text file, and outputs text to the screen in color.
I would also like to see a tail function that would do this, but haven't found one yet.
This function can also be improved - I'd appreciate any help on how to make it better.
function multigrep(){
#THIS WORKS - Recreate this, using input parameters
#sed -En '/(App)|(Spe)/p' ./flashlog.txt;
filename="/Users/stevewarren/Library/Preferences/Macromedia/Flash\ Player/Logs/flashlog.txt";
paramString="";
for element in "$@"
do
#echo $element;
paramString="$paramString($element)|";
done
#TRIM FINAL | OFF PARAMSTRING
paramString=${paramString:0:${#paramString}-1};
#CREATE SED EXPRESSION - '/($1)|($2)|(...)/p'
paramString="'/$paramString/p'";
#CREATE SED FUNCTION, CALL ON FILE
paramString="sed -En $paramString ./flashlog.txt"
echo $paramString;
echo "${txtbld}$(tput setaf 7)" > ./flashlog_output.txt;
eval $paramString >> ./flashlog_output.txt;
echo >> ./flashlog_output.txt;
#cat ./flashlog_output.txt;
cat ./flashlog_output.txt | while read LINE
do
[[ $1 && ${1-x} ]] &&
if grep -q $1 <<<$LINE; then
echo "$(tput setaf 3)$LINE"
fi
[[ $2 && ${2-x} ]] &&
if grep -q $2 <<<$LINE; then
echo "$(tput setaf 7)$LINE"
fi
[[ $3 && ${3-x} ]] &&
if grep -q $3 <<<$LINE; then
echo "$(tput setaf 6)$LINE"
fi
done
}
sure !
I wrote long a go a function called "egrepi", based on the 8 color variables definitions. This works ONLY piped like a "tail -f" colored function.
1. setColors
first, the color variables function to be called at first:
setColors ()
{
set -a
which printf >/dev/null 2>&1 && print=printf || print=print # Mandriva doesn't know about printf
hide='eval tput civis'
show='eval tput cnorm'
CLS=$(tput clear)
bel=$(tput bel)
case ${UNAME} in
AIX)
# text / foreground
N=$(${print} '\033[1;30m')
n=$(${print} '\033[0;30m')
R=$(${print} '\033[1;31m')
r=$(${print} '\033[0;31m')
G=$(${print} '\033[1;32m')
g=$(${print} '\033[0;32m')
Y=$(${print} '\033[1;33m')
y=$(${print} '\033[0;33m')
B=$(${print} '\033[1;34m')
b=$(${print} '\033[0;34m')
M=$(${print} '\033[1;35m')
m=$(${print} '\033[0;35m')
C=$(${print} '\033[1;36m')
c=$(${print} '\033[0;36m')
W=$(${print} '\033[1;37m')
w=$(${print} '\033[0;37m')
END=$(${print} '\033[0m')
# background
RN=$(${print} '\033[6;40m')
Rn=$(${print} '\033[40m')
RR=$(${print} '\033[6;41m')
Rr=$(${print} '\033[41m')
RG=$(${print} '\033[6;42m')
Rg=$(${print} '\033[42m')
RY=$(${print} '\033[6;43m')
Ry=$(${print} '\033[43m')
RB=$(${print} '\033[6;44m')
Rb=$(${print} '\033[44m')
RM=$(${print} '\033[6;45m')
Rm=$(${print} '\033[45m')
RC=$(${print} '\033[6;46m')
Rc=$(${print} '\033[46m')
RW=$(${print} '\033[6;47m')
Rw=$(${print} '\033[47m')
HIGH=$(tput bold)
SMUL=$(tput smul)
RMUL=$(tput rmul)
BLINK=$(tput blink)
REVERSE=$(tput smso)
REVERSO=$(tput rmso)
;;
*)
# text / foreground
n=$(tput setaf 0)
r=$(tput setaf 1)
g=$(tput setaf 2)
y=$(tput setaf 3)
b=$(tput setaf 4)
m=$(tput setaf 5)
c=$(tput setaf 6)
w=$(tput setaf 7)
N=$(tput setaf 8)
R=$(tput setaf 9)
G=$(tput setaf 10)
Y=$(tput setaf 11)
B=$(tput setaf 12)
M=$(tput setaf 13)
C=$(tput setaf 14)
W=$(tput setaf 15)
END=$(tput sgr0)
HIGH=$(tput bold)
SMUL=$(tput smul)
RMUL=$(tput rmul)
BLINK=$(tput blink)
REVERSE=$(tput smso)
REVERSO=$(tput rmso)
# background
Rn=$(tput setab 0)
Rr=$(tput setab 1)
Rg=$(tput setab 2)
Ry=$(tput setab 3)
Rb=$(tput setab 4)
Rm=$(tput setab 5)
Rc=$(tput setab 6)
Rw=$(tput setab 7)
RN=$(tput setab 8)
RR=$(tput setab 9)
RG=$(tput setab 10)
RY=$(tput setab 11)
RB=$(tput setab 12)
RM=$(tput setab 13)
RC=$(tput setab 14)
RW=$(tput setab 15)
;;
esac
BLUEf=${B}
BLUE=${b}
REDf=${R}
RED=${r}
GREENf=${G}
GREEN=${g}
YELLOWf=${Y}
YELLOW=${y}
MANGENTAf=${M}
MANGENTA=${m}
WHITEf=${W}
WHITE=${w}
CYANf=${C}
CYAN=${c}
OK="${RG}${n}OK${END}"
KO="${RR}${n}KO${END}"
NA="${N}NA${END}"
COLORIZE='eval sed -e "s/{END}/${END}/g" -e "s/{HIGH}/${HIGH}/g" -e "s/{SMUL}/${SMUL}/g" -e "s/{RMUL}/${RMUL}/g" -e "s/{BLINK}/${BLINK}/g" -e "s/{REVERSE}/${REVERSE}/g" -e "s/{REVERSO}/${REVERSO}/g"'
LOWS=' -e "s/{n}/${n}/g" -e "s/{r}/${r}/g" -e "s/{g}/${g}/g" -e "s/{y}/${y}/g" -e "s/{b}/${b}/g" -e "s/{m}/${m}/g" -e "s/{c}/${c}/g" -e "s/{w}/${w}/g"'
HIGHS=' -e "s/{N}/${N}/g" -e "s/{R}/${R}/g" -e "s/{G}/${G}/g" -e "s/{Y}/${Y}/g" -e "s/{B}/${B}/g" -e "s/{M}/${M}/g" -e "s/{C}/${C}/g" -e "s/{W}/${W}/g"'
REVLOWS=' -e "s/{Rn}/${Rn}/g" -e "s/{Rr}/${Rr}/g" -e "s/{Rg}/${Rg}/g" -e "s/{Ry}/${Ry}/g" -e "s/{Rb}/${Rb}/g" -e "s/{Rm}/${Rm}/g" -e "s/{Rc}/${Rc}/g" -e "s/{Rw}/${Rw}/g"'
REVHIGHS=' -e "s/{RN}/${RN}/g" -e "s/{RR}/${RR}/g" -e "s/{RG}/${RG}/g" -e "s/{RY}/${RY}/g" -e "s/{RB}/${RB}/g" -e "s/{RM}/${RM}/g" -e "s/{RC}/${RC}/g" -e "s/{RW}/${RW}/g"'
# COLORIZE Usage:
# command |${COLORIZE} ${LOWS} ${HIGHS} ${REVLOWS} ${REVHIGHS}
set +a
}
2. egrepi
and the egrepi function, effective and elegant: color cycling between 8 or more colors (your needs) AND tested under 3 different unix OS, with comments :
# egrepi() egrep with 8 REVERSE cyclic colorations on regexps almost like egrep
# egrepi
# current script will work for KSH88, KSH93, bash 2+, zsh, under AIX / Linux / SunOS
egrepi ()
{
args=$*
# colorList=wBcgymrN # KSH93 or bash 3+, not for AIX
# set -A color # needed with older sh
color[0]=$Rw; color[1]=$RB; color[2]=$Rc; color[3]=$Rg; color[4]=$Ry; color[5]=$Rm; color[6]=$Rr; color[7]=$RN; # this is the only one AIX solution
i=0
unset argsToGrep argsSedColor argsPerlColor
for arg in ${args}
do
[ "${arg}" == "." ] && arg=\\. # if you wanna grep "."
# color=R${colorList:((${RANDOM: -1:1})):1} # bash RANDOMized colors
# color=R${colorList:$i:1} && let i++ && ((i==8)) && i=0 # KSH93 or bash 3+, not for AIX
argsToGrep="${argsToGrep}${argsToGrep:+|}${arg}"
# argsSedColor="${argsSedColor} -e s#${arg}#$n${!color}&${w}#gI" # AIX KSH88 do not recognise this fucking variable double expansion
# argsSedColor="${argsSedColor} -e s#${arg}#$n${color[$i]}&${w}#gI" # AIX neither do include sed with Ignore case
argsPerlColor="${argsPerlColor}${argsPerlColor:+,}s#${arg}#$n${color[$i]}$&${END}#gi" # So: gotta use perl
let i+=1 && ((i==8)) && i=0 # AIX KSH88 do not recognise "let i++"
done
# egrep -i "${argsToGrep}" | sed ${argsSedColor} | egrep -v "grep|sed" # AIX sed incompatibility with Ignore case
# (($# > 0)) && (egrep -i "${argsToGrep}" | perl -p -e ${argsPerlColor}) || cat # this line colors & grep the words, will NOT act as "tail -f"
(($# > 0)) && (perl -p -e ${argsPerlColor}) || cat # this line just colors the words
}
3. Usage
command | egrepi word1 .. wordN
Publishes some time ago Node Js utility - log-color-highlight
tail -f file | lch -red error warn -green success
lch -f file -red.bold error warn -underline.bgGreen success
Based on the @this post, I've created a solution which shows dynamic tail output from the multiple logs files and returns coloured warning and error messages as below:
tail -f -n 5 application.log debug.log| perl -pe 's#WARNING#\x1b[33m$&#; s#ERROR#\x1b[31m$&#; s#foo#\x1b[32m$&#'
No installation needed. Hope this helps someone.
Working solution on Mac
Tried a bunch of things that just didn't work because of some escaping issue.
Eventually found a working solution:
tail -f example.log | sed \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"
A quick way to show it working:
echo " [timestamp] production.FATAL Some Message\n" \
"[timestamp] production.ERROR Some Message\n" \
"[timestamp] production.WARNING Some Message\n" \
"[timestamp] production.INFO Some Message\n" \
"[timestamp] production.DEBUG Some Message\n" | sed \
-e "s/FATAL/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/ERROR/"$'\e[31m'"&"$'\e[m'"/" \
-e "s/WARNING/"$'\e[33m'"&"$'\e[m'"/" \
-e "s/INFO/"$'\e[32m'"&"$'\e[m'"/" \
-e "s/DEBUG/"$'\e[34m'"&"$'\e[m'"/"
Note: this won't hide any logs, just color the parts needed
sed to post-process the raw output and introduce color escape codes was already mentioned in the answer by @Gilles. Please review your answer and decide whether your approach is sufficiently distinct to warrant a post of its own, or if it should rather be an edit to add details to the mentioned answer.
– AdminBee
Nov 09 '21 at 08:16
sed, it doesn't work on Mac, I've tried it. The start of the line gets replaced with o033[32m and end o033[39m, and its not coloured. I believe this is because the way unix escapes part of it. Ive searched high and wide for a solution to this, but nothing worked.
– Oli Girling
Nov 09 '21 at 09:40
sudo apt install grc
grc tail /var/log/syslog
alias tail='grc tail'
alias tail='grc tail' here which seems unique among the existing answers. That does address the question "What kind of alias can I setup for a tail command...`". Perhaps a suggested edit would have been better?
– Jeff Schaller
Feb 22 '22 at 19:35
There is a new open source tool (Logdy.dev) that satisfies the need. You can use TypeScript to parse and transform the content of log messages. All of that in a web UI that comes filters/facets.
Update: you can style each individual row or cell by applying a style in a Message or CellHandler handler.
For example, here is a code that makes the background of a column with an error level cell row red. The code is applied for a level column.
(line: Message): CellHandler => {
return {
text: line.json_content.level,
style: {
background: line.json_content.level === 'error' ? "red" : ""
},
facets: [
{ name: "Level", value: line.json_content.level }
]
}
}
sed: https://stackoverflow.com/a/14691971/52074 – Trevor Boyd Smith Sep 14 '18 at 18:45