This question already has answers here:
Bash comparison operator always true
(1 answer)
How to assign the output of a Bash command to a variable? [duplicate]
(5 answers)
Closed 2 years ago.
i am trying to execute a IF condition inside a while loop, But the IF condition isn't working as variables aren't expanding! kindly guide me through the proper way to compare two variables in IF condition
Note - if you can see the error log - DATE was expanding thou! problem with mdate
DATE=`date +"%Y-%m-%d"`
cat path/temp_b | while read file
do
echo 'phase2'
mtime=$(stat -c '%y' $Src_Dir/$file)
echo $mtime
mdate= echo $mtime | cut -d ' ' -f1
echo $mdate
echo $DATE
if ["$mdate"=="$DATE"]; then
"$file" > path/tempc
else
echo 'hi'
fi
done
**Error log -
phase2
2020-05-07 05:22:28.000000000 -0400
2020-05-07
2020-07-21
./test1.ksh: line 37: [==2020-07-21]: command not found
hi**
Change your if statement like:
if [ "$mdate" == "$DATE" ]; then
Explanation: if in bash needs to have square brackets, operator, and operand to be space-separated.
Related
This question already has answers here:
I just assigned a variable, but echo $variable shows something else
(7 answers)
When should I double-quote a parameter expansion? [duplicate]
(1 answer)
Closed 5 months ago.
If I have a file containing newlines, the below script will output the file as is, with newlines:
#!/bin/bash
FOO=$(cat filename.yaml)
echo "$FOO"
but
#!/bin/bash
FOO=$(cat filename.yaml)
FOO=$(echo $FOO)
echo "$FOO"
outputs the file all on one line. How come?
I do not recommend storing the contents of entire files in a single variable. In my experience that can have unpredictable results.
/usr/bin/env bash -x
index=$(wc -l filename.yaml | cut -d' ' -f1)
count=1
next () {
[[ "${count}" -lt "${index}" ]] && main
[[ "${count}" -eq "${index}" ]] && exit 0
}
main () {
line=$(sed -n "${count}p" filename.yaml)
echo "var${count}=${line}" >> varfile
count=$(($count+1))
next
}
next
If you source varfile at the start of another script, it will give you every line from that file, in its' own variable.
This question already has answers here:
Why should there be spaces around '[' and ']' in Bash?
(5 answers)
Closed 9 months ago.
I try to write simple script to read temperature:
cpu=$(cat /sys/class/thermal/thermal_zone*/temp)
if [$cpu -ge 50000]; then
echo "OK"
else
echo "Not OK"
fi
echo $cpu is fine: 64000 but script output is:
myscript.sh: 2: [64000: not found
Not OK
What is wrong with line 2?
Thank You.
You want to make a few changes here:
Add a space between the [ and the $cpu, and before the ] (as per the comments above)
Place the $cpu into double quotes, to avoid unexpected results
Handle the possibility of maximum values, by picking up the maximum (or minimum, or average).
cpu="$(cat /sys/class/thermal/thermal_zone*/temp | sort -nr | head -1)"
if [ "$cpu" -ge 50000 ] ; then
echo "OK"
else
echo "NOT"
fi
If you prefer the space-less expressions, you can use the arithmetic expressions
cpu="$(cat /sys/class/thermal/thermal_zone*/temp | sort -nr | head -1)"
if ((cpu>50000)) ; then
echo "OK"
else
echo "NOT"
fi
This question already has answers here:
A variable modified inside a while loop is not remembered
(8 answers)
Closed 2 years ago.
I am trying to insert values in to an array in a loop as follows:
branches_to_delete=()
cat branches.txt | while read branch_name
do
BRANCH_COUNT=$(git ls-remote | grep -w $branch_name | wc -l)
if [ $BRANCH_COUNT -eq 0 ]; then
echo "Branch does not exist"
branches_to_delete+=($branch_name)
elif [ $BRANCH_COUNT -eq 1 ]; then
echo "Branch exists"
else
echo "Not valid result"
fi
done
echo "Loop finished"
echo ${branches_to_delete[#]}
But when I printout branches_to_delete it is actually empty.
What am I doing wrong here?
With the pipe from cat branches.txt into the read loop, you create a subshell that cannot access the parent shell's branches_to_delete array.
You can fix this by avoiding the pipe and saving a useless use of cat:
branches_to_delete=()
while read branch_name; do
...
done < branches.txt
(Make sure nothing in ... reads from read's stdin. You'll notice if something is missing).
This question already has answers here:
Command not found error in Bash variable assignment
(5 answers)
Closed 7 years ago.
When I run my script:
#!/usr/bin/env bash
read NUM
case $NUM in
1)
current_id = "$$"
ps -ef > file1.txt
echo "$current_id"
while [ $current_id -ne 1 ]
do
current_id =$( cat file1.txt | awk '(if ( $s == '$current_id' ) print $3;)')
echo " | "
echo " v "
echo $current_id
done
echo "";;
I get the error:
current_id: command not found
[: -ne: unary operator expected
I am trying to find the child-parent tree with this method. Is there something wrong with my syntax? Or is the current_id = "$$" not allowed? Thank for your help.
In assignment, there must not be a space before =
current_id =$(...) # tries to run a program called current_id, which does not exist
current_id=$(...) # assigns a value to variable
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Bash Script - Variable Scope in Do-While loop
In the following code, it prints the correct value of i in inner while loop, but it prints 0 after it comes out of inner while loop:
string="Medicine"
for file in *
do
i=0
cat $file | while read line
do
echo $line
if [ "$line" == "$string" ];
then
i=`expr $i + 1`
echo $i
fi
done
echo $i
done
By default variables have global scope in shell scripting, which make "i " global. if you want to make a variable as local ,use keyword "local" , for eg: local i=0
for more details check the link, http://www.bashguru.com/2008/06/bash-variables-scope.html