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Peter.O
Peter.O
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# Create a test file
  echo "going abc"  >junk
  echo "going def" >>junk
  echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
# Assign file to fd 3, and open it r/w
  exec 3<> junk  
#
# Choose a unique filename to hold the new file size  and the pid 
# of the semi-asynchrounous process to which 'tee' streams the new file..  
  [[ ! -d "/tmp/$USER" ]] && mkdir "/tmp/$USER" 
  f_pid_size="/tmp/$USER/pid_size.$(date '+%N')" # %N is a GNU extension: nanoseconds
  [[ -f "$f_pid_size" ]] && { echo "ERROR: Work file already exists: '$f_pid_size'" ;exit 1 ; }
#
# run 'sed' output to 'tee' ... 
#  to modify the file in-situ, and to count the bytes  
  <junk sed -e "s/going //" |tee >(echo -n "$BASHPID " >"$f_pid_size" ;wc -c >>"$f_pid_size") >&3
#
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
# The byte-counting process is not a child-process, 
# so 'wait' doesn't work... but wait we must...  
  pid_size=($(cat "$f_pid_size")) ;pid=${pid_size[0]}  
  # $f_pid_size may initially contain only the pid... 
  # get the size when pid termination is assured
  while [[ "$pid" != "" ]] ; do
    if ! kill -0 "$pid" 2>/dev/null; then
       pid=""  # pid has terminated. get the byte count
       pid_size=($(cat "$f_pid_size")) ;size=${pid_size[1]}
    fi
  done
  rm "$f_pid_size"
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#
  exec 3>&- # close fd 3.
  newsize=$(cat newsize)
  echo "# MODIFIED file (before truncating)";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat junk
#
 truncate -s $newsize junk
 echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat junk
#
exit

# Create a test file
  echo "going abc"  >junk
  echo "going def" >>junk
  echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
# Assign file to fd 3, and open it r/w
  exec 3<> junk  
#
# Choose a unique filename to hold the new file size  and the pid 
# of the semi-asynchrounous process to which 'tee' streams the new file..  
  [[ ! -d "/tmp/$USER" ]] && mkdir "/tmp/$USER" 
  f_pid_size="/tmp/$USER/pid_size.$(date '+%N')" # %N is a GNU extension: nanoseconds
  [[ -f "$f_pid_size" ]] && { echo "ERROR: Work file already exists: '$f_pid_size'" ;exit 1 ; }
#
# run 'sed' output to 'tee' ... 
#  to modify the file in-situ, and to count the bytes  
  <junk sed -e "s/going //" |tee >(echo -n "$BASHPID " >"$f_pid_size" ;wc -c >>"$f_pid_size") >&3
#
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
# The byte-counting process is not a child-process, 
# so 'wait' doesn't work... but wait we must...  
  pid_size=($(cat "$f_pid_size")) ;pid=${pid_size[0]}  
  # $f_pid_size may initially contain only the pid... 
  # get the size when pid termination is assured
  if ! kill -0 "$pid" 2>/dev/null; then
    # pid has terminated. get the byte count
     pid_size=($(cat "$f_pid_size")) ;size=${pid_size[1]}
  fi
  rm "$f_pid_size"
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#
  exec 3>&- # close fd 3.
  newsize=$(cat newsize)
  echo "# MODIFIED file (before truncating)";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat junk
#
 truncate -s $newsize junk
 echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat junk
#
exit

# Create a test file
  echo "going abc"  >junk
  echo "going def" >>junk
  echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
# Assign file to fd 3, and open it r/w
  exec 3<> junk  
#
# Choose a unique filename to hold the new file size  and the pid 
# of the semi-asynchrounous process to which 'tee' streams the new file..  
  [[ ! -d "/tmp/$USER" ]] && mkdir "/tmp/$USER" 
  f_pid_size="/tmp/$USER/pid_size.$(date '+%N')" # %N is a GNU extension: nanoseconds
  [[ -f "$f_pid_size" ]] && { echo "ERROR: Work file already exists: '$f_pid_size'" ;exit 1 ; }
#
# run 'sed' output to 'tee' ... 
#  to modify the file in-situ, and to count the bytes  
  <junk sed -e "s/going //" |tee >(echo -n "$BASHPID " >"$f_pid_size" ;wc -c >>"$f_pid_size") >&3
#
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
# The byte-counting process is not a child-process, 
# so 'wait' doesn't work... but wait we must...  
  pid_size=($(cat "$f_pid_size")) ;pid=${pid_size[0]}  
  # $f_pid_size may initially contain only the pid... 
  # get the size when pid termination is assured
  while [[ "$pid" != "" ]] ; do
    if ! kill -0 "$pid" 2>/dev/null; then
       pid=""  # pid has terminated. get the byte count
       pid_size=($(cat "$f_pid_size")) ;size=${pid_size[1]}
    fi
  done
  rm "$f_pid_size"
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#
  exec 3>&- # close fd 3.
  newsize=$(cat newsize)
  echo "# MODIFIED file (before truncating)";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat junk
#
 truncate -s $newsize junk
 echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat junk
#
exit
added wait of process to terminate; deleted 8 characters in body
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Peter.O
Peter.O
  • 33.8k
  • 32
  • 120
  • 167

Here is the script (uses: bash variable $BASHPID )

echo# "goingCreate abc"a test >junkfile
  #echo just"going aabc" test file>junk
  echo "going def" >>junk
  echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
exec 3<> junk  # Assign file to fd 3, and open it r/w
  exec 3<> junk  
#
# Choose a unique filename to hold the new file size  and the pid 
# of the semi-asynchrounous process to which 'tee' streams the new file..  
  [[ ! -d "/tmp/$USER" ]] && mkdir "/tmp/$USER" 
  f_pid_size="/tmp/$USER/pid_size.$(date '+%N')" # %N is a GNU extension: nanoseconds
  [[ -f "$f_pid_size" ]] && { echo "ERROR: Work file already exists: '$f_pid_size'" ;exit 1 ; }
#
# run 'sed' output to 'tee' ... 
#  to modify the file in-situ, and to count the bytes  
  <junk sed -e "s/going //" |tee >(wcecho -n "$BASHPID " >"$f_pid_size" ;wc -c >newsize>>"$f_pid_size") >&3
#
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
# The byte-counting process is not a child-process, 
# TODO:so dedicated'wait' doesn't work... but wait logicwe formust... the newsize 
 process topid_size=($(cat finish,"$f_pid_size")) as;pid=${pid_size[0]} it runs 
 asynchronously # $f_pid_size may initially contain only the pid... see: 
 http: # get the size when pid termination is assured
  if ! kill -0 "$pid" 2>/dev/unix.stackexchangenull; then
    # pid has terminated.com/questions/10623/a-tee-process-is-truncating-its-stdout-when-writing-a-file get the byte count
     pid_size=($(cat "$f_pid_size")) ;size=${pid_size[1]}
  fi
  rm "$f_pid_size"
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#
  exec 3>&- # close fd 3.
  newsize=$(cat newsize)
  echo "# MODIFIED file";catfile (before truncating)";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk
#
 truncate -s $newsize junk
 echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk
#
exit

Here is the script

echo "going abc"  >junk  # just a test file
echo "going def" >>junk
echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
exec 3<> junk  # Assign file to fd 3, and open it r/w
<junk sed -e "s/going //" |tee >(wc -c >newsize) >&3 
# TODO: dedicated wait logic for the newsize process to finish, as it runs asynchronously... see: http://unix.stackexchange.com/questions/10623/a-tee-process-is-truncating-its-stdout-when-writing-a-file
exec 3>&- # close fd 3.
newsize=$(cat newsize)
echo "# MODIFIED file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk
#
truncate -s $newsize junk
echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk

Here is the script (uses: bash variable $BASHPID )

# Create a test file
  echo "going abc"  >junk
  echo "going def" >>junk
  echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
# Assign file to fd 3, and open it r/w
  exec 3<> junk  
#
# Choose a unique filename to hold the new file size  and the pid 
# of the semi-asynchrounous process to which 'tee' streams the new file..  
  [[ ! -d "/tmp/$USER" ]] && mkdir "/tmp/$USER" 
  f_pid_size="/tmp/$USER/pid_size.$(date '+%N')" # %N is a GNU extension: nanoseconds
  [[ -f "$f_pid_size" ]] && { echo "ERROR: Work file already exists: '$f_pid_size'" ;exit 1 ; }
#
# run 'sed' output to 'tee' ... 
#  to modify the file in-situ, and to count the bytes  
  <junk sed -e "s/going //" |tee >(echo -n "$BASHPID " >"$f_pid_size" ;wc -c >>"$f_pid_size") >&3
#
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
# The byte-counting process is not a child-process, 
# so 'wait' doesn't work... but wait we must...   
  pid_size=($(cat "$f_pid_size")) ;pid=${pid_size[0]}   
  # $f_pid_size may initially contain only the pid...  
  # get the size when pid termination is assured
  if ! kill -0 "$pid" 2>/dev/null; then
    # pid has terminated. get the byte count
     pid_size=($(cat "$f_pid_size")) ;size=${pid_size[1]}
  fi
  rm "$f_pid_size"
#@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
#
  exec 3>&- # close fd 3.
  newsize=$(cat newsize)
  echo "# MODIFIED file (before truncating)";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat junk
#
 truncate -s $newsize junk
 echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat junk
#
exit
deleted 1 characters in body
Source Link
Peter.O
Peter.O
  • 33.8k
  • 32
  • 120
  • 167

You can use a bash read/write file descriptor to open your file (andto overwrite it in-situ), then sed and truncate ... but of course, don't ever allow your changes to be larger than the amount of data read so far.

Here is the script

echo "going abc"  >junk  # just a test file
echo "going def" >>junk
echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
exec 3<> junk  # Assign file to fd 3, and open it r/w
<junk sed -e "s/going //" |tee >(wc -c >newsize) >&3 
# TODO: dedicated wait logic for the newsize process to finish, as it runs asynchronously... see: http://unix.stackexchange.com/questions/10623/a-tee-process-is-truncating-its-stdout-when-writing-a-file
exec 3>&- # close fd 3.
newsize=$(cat newsize)
echo "# MODIFIED file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk
#
truncate -s $newsize junk
echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk

Here is the test output

# ORIGINAL file
going abc
going def
# 2 lines, 20 bytes

# MODIFIED file (before truncating)
abc
def
c
going def
# 4 lines, 20 bytes

# NEW (truncated) file
abc
def
# 2 lines, 8 bytes

You can use a bash read/write file descriptor to open your file (and overwrite it in-situ), then sed and truncate ... but of course, don't ever allow your changes to be larger than the amount of data read so far.

Here is the script

echo "going abc"  >junk  # just a test file
echo "going def" >>junk
echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
exec 3<> junk  # Assign file to fd 3, and open it r/w
<junk sed -e "s/going //" |tee >(wc -c >newsize) >&3 
# TODO: dedicated wait logic for the newsize process to finish, as it runs asynchronously... see: http://unix.stackexchange.com/questions/10623/a-tee-process-is-truncating-its-stdout-when-writing-a-file
exec 3>&- # close fd 3.
newsize=$(cat newsize)
echo "# MODIFIED file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk
#
truncate -s $newsize junk
echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk

Here is the test output

# ORIGINAL file
going abc
going def
# 2 lines, 20 bytes

# MODIFIED file (before truncating)
abc
def
c
going def
# 4 lines, 20 bytes

# NEW (truncated) file
abc
def
# 2 lines, 8 bytes

You can use a bash read/write file descriptor to open your file (to overwrite it in-situ), then sed and truncate ... but of course, don't ever allow your changes to be larger than the amount of data read so far.

Here is the script

echo "going abc"  >junk  # just a test file
echo "going def" >>junk
echo "# ORIGINAL file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )
#
exec 3<> junk  # Assign file to fd 3, and open it r/w
<junk sed -e "s/going //" |tee >(wc -c >newsize) >&3 
# TODO: dedicated wait logic for the newsize process to finish, as it runs asynchronously... see: http://unix.stackexchange.com/questions/10623/a-tee-process-is-truncating-its-stdout-when-writing-a-file
exec 3>&- # close fd 3.
newsize=$(cat newsize)
echo "# MODIFIED file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk
#
truncate -s $newsize junk
echo "# NEW (truncated) file";cat junk |tee >( wc=($(wc)); echo "# ${wc[0]} lines, ${wc[2]} bytes" ;echo )  cat  junk

Here is the test output

# ORIGINAL file
going abc
going def
# 2 lines, 20 bytes

# MODIFIED file (before truncating)
abc
def
c
going def
# 4 lines, 20 bytes

# NEW (truncated) file
abc
def
# 2 lines, 8 bytes
added 327 characters in body; edited body; deleted 106 characters in body; added 20 characters in body; deleted 14 characters in body
Source Link
Peter.O
Peter.O
  • 33.8k
  • 32
  • 120
  • 167
Source Link
Peter.O
Peter.O
  • 33.8k
  • 32
  • 120
  • 167