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Old 05-29-2013, 07:03 AM   #1
ajaylinuxrk
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Registered: May 2013
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Trying to write a bash script need some suggesstions.


Gurus,

I want to write a bash script to read a line by line from a file and execute in a command and redirect the output to a file.I am able to think through the below syntax but not sure how to redirect the output of the command to another file.Need suggestions.

#/bin/bash

for i in "cat /tmp/file"
do
command | grep "$i"

done.

Thanks in Advance.
 
Old 05-29-2013, 07:07 AM   #2
shivaa
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Just try:
Code:
#/bin/bash
while read -r i
do
command | grep "$i" > /path/to/output.txt
done < /tmp/file
Use while+read instead of for loop for reading output from a file line by line. The > /path/to/output.txt part redirects output of the command into a file named /path/to/output.txt.
 
1 members found this post helpful.
Old 05-29-2013, 07:12 AM   #3
chrism01
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Given that each cmd is tun separately, you probably want '>>' i.e. append, instead of > (output), which will overwrite the file.
 
Old 05-29-2013, 11:11 AM   #4
Habitual
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Code:
REPORT=/home/c9admin/amn_ami_delete3.rpt
... stuff...
... stuff...
echo "" > "$REPORT" #truncates "$REPORT"
... stuff...
	do ec2-deregister $i >> "$REPORT" # appends output of each iteration into "$REPORT"
 
Old 05-29-2013, 12:00 PM   #5
grail
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A slight alternative to shivaa's example and allowing the incorporation of chrism01's suggestion:
Code:
while read -r line
do
    command | grep "$line"
done< /tmp/file > /path/to/output.txt
 
Old 05-30-2013, 06:32 PM   #6
David the H.
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If the "command" prints the same output every time, and you just want to capture all the matching lines from the file, then this would probably do you better:

Code:
command | grep -f /tmp/file > /path/to/output.txt
 
  


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