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====== BASH - Files - Parse a line from a file ======

There are many ways of doing this, depending on your needs.

----

===== Method 1 =====

Example file:

<file>
07/17 21:04:01 sndc addr unit 1 : hu P1 (TempLinc)
07/17 21:04:02 sndc func StatusReq : hc P
07/17 21:04:04 rcvi addr unit 15 : hu P15 (TempAck_5)
07/17 21:04:04 rcvi func Preset : level 11
07/17 21:04:04 Temperature = 78 : hu P0 (office_temp)
07/17 21:19:01 sndc addr unit 1 : hu P1 (TempLinc)
07/17 21:19:02 sndc func StatusReq : hc P
07/17 21:19:05 rcvi addr unit 15 : hu P15 (TempAck_5)
07/17 21:19:05 rcvi func Preset : level 11
07/17 21:19:05 Temperature = 78 : hu P0 (office_temp)
</file>


<code>
#!/bin/bash

fil=/home/test.log

# Test for existence of the test file
if [ -f $fil ]
then

  # Read through the file looking for the word Temperature =

  while read line
  do
    echo $line | grep -q Temperature
    if [ $? == 0 ]; then
    mytemp=`echo $line  | cut -d = -f2 | cut -d : -f1`
    echo "Current temperature is: $mytemp"
    fi
  done < $fil

fi
</code>

returns:

<code>
Current temperature is:  78 
Current temperature is:  78
</code>

<WRAP info>
**NOTE:**  The **-f** tests that the file exists.

Other options include:

  * **-b file**:  Checks if file is a block special file; if yes, then the condition becomes true.    [ -b $file ].
  * **-c file**:  Checks if file is a character special file; if yes, then the condition becomes true.    [ -c $file ].
  * **-d file**:  Checks if file is a directory; if yes, then the condition becomes true.     [ -d $file ].
  * **-e file**:  Checks if file exists; is true even if file is a directory but exists.  [ -e $file ].
  * **-f file**:  Checks if file is an ordinary file as opposed to a directory or special file; if yes, then the condition becomes true.  [ -f $file ].
  * **-g file**:  Checks if file has its set group ID (SGID) bit set; if yes, then the condition becomes true.    [ -g $file ].
  * **-k file**:  Checks if file has its sticky bit set; if yes, then the condition becomes true.     [ -k $file ].
  * **-p file**:  Checks if file is a named pipe; if yes, then the condition becomes true.    [ -p $file ].
  * **-r file**:  Checks if file is readable; if yes, then the condition becomes true.    [ -r $file ].
  * **-t file**:  Checks if file descriptor is open and associated with a terminal; if yes, then the condition becomes true.  [ -t $file ].
  * **-s file**:  Checks if file has size greater than 0; if yes, then condition becomes true.    [ -s $file ].
  * **-u file**:  Checks if file has its Set User ID (SUID) bit set; if yes, then the condition becomes true.     [ -u $file ].
  * **-w file**:  Checks if file is writable; if yes, then the condition becomes true.    [ -w $file ].
  * **-x file**:  Checks if file is executable; if yes, then the condition becomes true.  [ -x $file ].



</WRAP>


----

===== Only get last temperature record =====

<code>
#!/bin/bash
fil=/home/temp.log.ttyS0

if [ -f $fil ]
then

mytemp=`grep Temperature $fil | tail -1 | cut -d = -f2 | cut -d : -f1`
echo "Current temperature is: $mytemp"

fi
</code>