I run my safe shell script to make sure a binary is running
to check a binary is running I do following command
pidof prog.bin | awk '{print NF}'
is some system it gives me 0 when binary not running
and
in some systems it gives me NULL(nothing)
I can check the NULL using -z option but why awk command acting this way ??
Instead of pidof you can use:
pgrep -qf prog.bin
And check its exit status.
As per man pgrep:
-f Match against full argument lists. The default is to match against process names.
-q Do not write anything to standard output.
You can use this,
if [ `pidof 'NetworkManager'` ]; then
echo "Running"
else
echo "Not Running"
fi
One way to handle this sort of thing (undefined variables) in awk is like this:
echo hi | awk '{print a}'
compared with:
echo hi | awk '{print a || 0}'
0
One Liner for If else
[[ $(pidof 'NetworkManager') ]] && echo "Running" || echo "Not Running"
Try this:
pidof prog.bin | awk '{ if (NF!=0) print NF }'
Here's some tests with awk and NF:
$ # regular line of input
$ echo foo | awk '{print NF}'
1
$ # empty line
$ echo | awk '{print NF}'
0
$ # a word on input with no newline
$ printf "%s" nonewline | awk '{print NF}'
1
$ # no input, not even a newline
$ printf %s | awk '{print NF}'
# no output from awk
I suspect the pidof case is the last: not even a newline. To force a newline:
echo $(pidof prog) | ...
printf "%s\n" "$(pidof prog)" | ...
Related
Here is my string that needs to be parsed.
line='aaa vvv ccc'
I need to print the values one by one.
no_of_users=$(echo $line| wc -w)
If the no_of_users is greater than 1 then I need to print the values one by one.
aaa
vvv
ccc
I used this script.
if [ $no_of_users -gt 1 ]
then
for ((n=1;n<=$no_of_users;n++))
do
-- here is my issue ##echo 'user:'$n $line|awk -F ' ' -vno="${n}" 'BEGIN { print no }'
done
fi
In the { print no } I have to print the value in that position.
You may use this awk:
awk 'NF>1 {OFS="\n"; $1=$1} 1' <<< "$line"
aaa
vvv
ccc
What it does:
NF>1: If number of fields are greater than 1
OFS="\n": Set output field separator to \n
$1=$1: Force restructure of a record
1: Print a record
1st solution: Within single awk could you please try following. Where var is an awk variable which has shell variable line value in it.
awk -v var="$line" '
BEGIN{
num=split(var,arr," ")
if(num>1){
for(i=1;i<=num;i++){ print arr[i] }
}
}'
Explanation: Adding detailed explanation for above.
awk -v var="$line" ' ##Starting awk program and creating var variable which has line shell variable value in it.
BEGIN{ ##Starting BEGIN section of program from here.
num=split(var,arr," ") ##Splitting var into array arr here. Saving its total length into variable num to check it later.
if(num>1){ ##Checking condition if num is greater than 1 then do following.
for(i=1;i<=num;i++){ print arr[i] } ##Running for loop from i=1 to till value of num here and printing arr value with index i here.
}
}'
2nd solution: Adding one more solution tested and written in GNU awk.
echo "$line" | awk -v RS= -v OFS="\n" 'NF>1{$1=$1;print}'
Another option:
if [ $no_of_users -gt 1 ]
then
for ((n=1;n<=$no_of_users;n++))
do
echo 'user:'$n $(echo $line|awk -F ' ' -v x=$n '{printf $x }')
done
fi
You can use grep
echo $line | grep -o '[a-z][a-z]*'
Also with awk:
awk '{print $1, $2, $3}' OFS='\n' <<< "$line"
aaa
vvv
ccc
the key is setting OFS='\n'
Or a really toughie:
printf "%s\n" $line
(note: $line is unquoted)
printf will consume all words in line with word-splitting applied so each word is taken as a single input.
Example Use/Output
$ line='aaa vvv ccc'; printf "%s\n" $line
aaa
vvv
ccc
Using bash:
$ line='aaa vvv'ccc'
$ [[ $line =~ \ ]] && echo -e ${line// /\\n}
aaa
vvv
ccc
$ line=aaa
$ [[ $line =~ \ ]] && echo -e ${line// /\\n}
$
If you are on another shell:
$ line="foo bar baz" bash -c '[[ $line =~ \ ]] && echo -e ${line// /\\n}'
grep -Eq '[[:space:]]' <<< "$line" && xargs printf "%s\n" <<< $line
Do a silent grep for a space in the variable, if true, print with names on separate lines.
awk -v OFS='\n' 'NF>1{$1=$1; print}'
e.g.
$ line='aaa vvv ccc'
$ echo "$line" | awk -v OFS='\n' 'NF>1{$1=$1; print}'
aaa
vvv
ccc
$ line='aaa'
$ echo "$line" | awk -v OFS='\n' 'NF>1{$1=$1; print}'
$
another golfed awk variation
$ awk 'gsub(FS,RS)'
only print if there is a substitution.
I need to get only numbers from this:
release/M_0.1.0
thus, need to extract with bash to have in output this:
0.1.0.
I have tried this but cannot finish it:
echo "release/M_0.1.0" | awk -F'/' '{print $2}'
And what about if given such string? relea234se/sdf23_4Mm0.1.0.8. How to get only 0.1.0.8? Please pay attention that this can be random digits such as 0.2 or 1.9.1.
Please check if this grep command works
echo "release/M_0.1.0" | egrep -o '[0-9.]+'
You could also use general parameter expansion parsing to literally remove characters up through the last that isn't digits or dots.
$: ver() { echo "${1//*[^.0-9]/}"; }
$: ver release/M_0.1.0
0.1.0
$: ver relea234se/sdf23_4Mm0.1.0.8
0.1.0.8
With sed you can do:
echo "release/M_0.1.0" | sed 's#.*_##'
Output:
0.1.0
Considering that your Input_file will be same as shown samples.
echo "$var" | awk -F'_' '{print $2}'
OR could use sub:
echo "$var" | awk '{sub(/.*_/,"")} 1'
With simple bash you could use:
echo "${var#*_}"
echo release/M_0.1.0 | awk -F\_ '{print $2}'
0.1.0
Take your pick:
$ var='relea234se/sdf23_4Mm0.1.0.8'
$ [[ $var =~ .*[^0-9.](.*) ]] && echo "${BASH_REMATCH[1]}"
0.1.0.8
$ echo "$var" | sed 's/.*[^0-9.]//'
0.1.0.8
$ echo "$var" | awk -F'[^0-9.]' '{print $NF}'
0.1.0.8
if data in d file, tried on gnu sed:
sed -E 's/relea.*/.*([0-9][0-9.]*)$/\1/' d
Would it be possible to print the filename used to redirect STDERR, given the sample command below:
command.sh 2>file.err
Code in command.sh:
#!/bin/sh
ls -l non_existing_file.txt
echo "STDERR file is: $stderrFilename" # variable should print file.err
It's a little risky, but you could try parsing AIX's procfiles output. It involves capturing the major and minor numbers of the stderr device, along with the inode number, then looking for the corresponding device, its mountpoint, and then using find to look for the file with the given inode number:
#!/bin/sh
dev=$(procfiles $$ | awk '$1 == "2:" { print substr($4, 5) }')
inode=$(procfiles $$ | awk '$1 == "2:" { print substr($5, 5) }')
major=${dev%%,*}
minor=${dev##*,}
if [ "$major}" -eq 0 ]
then
echo I give up, the major number is zero
exit 1
fi
for file in /dev/*
do
[ -b "$file" ] || continue
if istat "$file" | grep -q "^Major Device ${major}.*Minor Device ${minor}$"
then
break
fi
done
fs=$(mount | awk '$1 == "'"${file}"'" { print $2 }')
stderrFilename=$(find "$fs" -inum "$inode")
I made a solution using history. Not sure if there is an easier way to do this ( or a proper one).
#!/bin/sh
stderrfname=`history | tail -1 | awk '{ print $3 }' | sed "s/.*>//"`
echo "STDERR file is: $stderrfname"
How can I use IFS and awk $2 value on the same line?
ex.
array=(
element:5001
element:5002
element:5003
element:5004
)
IFS=':'
for i in "${array[#]}"
do
set -- $i
part1=$1
part2=$2
cd $part1
# this following line is where I am having the issue.
# $2 equal to part2 from the string split, but the $2 to be
# awk value for $2
echo "$(ps aux | grep '[s]omething --port '$2'' | awk '{print $2}')"
# use part2 later in code
done
Presently, I am only able to use $2 from IFS split.
Note: I have seen post about using the -v option with awk but I believe that is when you want to set a value to run against awk. I would like to print $2 generated from awk.
Thanks to #Barmar and #l0b0.
I need to fix my quotes.
...
echo $(ps aux | grep '[s]omething --port '$2 | awk '{print $2}')
...
I have this command which executes correctly if run directly on the terminal.
awk '/word/ {print NR}' file.txt | head -n 1
The purpose is to find the line number of the line on which the word 'word' first appears in file.txt.
But when I put it in a script file, it doens't seem to work.
#! /bin/sh
if [ $# -ne 2 ]
then
echo "Usage: $0 <word> <filename>"
exit 1
fi
awk '/$1/ {print NR}' $2 | head -n 1
So what did I do wrong?
Thanks,
Replace the single quotes with double quotes so that the $1 is evaluated by the shell:
awk "/$1/ {print NR}" $2 | head -n 1
In the shell, single-quotes prevent parameter-substitution; so if your script is invoked like this:
script.sh word
then you want to run this AWK program:
/word/ {print NR}
but you're actually running this one:
/$1/ {print NR}
and needless to say, AWK has no idea what $1 is supposed to be.
To fix this, change your single-quotes to double-quotes:
awk "/$1/ {print NR}" $2 | head -n 1
so that the shell will substitute word for $1.
You should use AWK's variable passing feature:
awk -v patt="$1" '$0 ~ patt {print NR; exit}' "$2"
The exit makes the head -1 unnecessary.
you could also pass the value as a variable to awk:
awk -v varA=$1 '{if(match($0,varA)>0){print NR;}}' $2 | head -n 1
Seems more cumbersome than the above, but illustrates passing vars.