bash echo number of lines of file given in a bash variable without the file name

Question

I have the following three constructs in a bash script   NUMOFLINES   wc -l  JAVA TAGS FILE  echo  NUMOFLINES  lines   echo   wc -l  JAVA TAGS FILE   lines   echo    wc -l  JAVA TAGS FILE  lines    And they both produce identical output when the script is run   121711  home slash  java base tag lines 121711  home slash  java base tag lines 121711  home slash  java base tag lines   I e  the name of the file is also echoed  which I don t want to   Why do these scriplets fail and how should I output a clean   121711 lines

User · Answer

wc can t get the filename if you don t give it one   wc -l  lt    JAVA TAGS FILE

User · Answer

An Example Using Your Own Data  You can avoid having your filename embedded in the NUMOFLINES variable by using redirection from JAVA TAGS FILE  rather than passing the filename as an argument to wc  For example   NUMOFLINES   wc -l  lt    JAVA TAGS FILE     Explanation  Use Pipes or Redirection to Avoid Filenames in Output  The wc utility will not print the name of the file in its output if input is taken from a pipe or redirection operator  Consider these various examples     wc shows filename when the file is an argument   wc -l  etc passwd 41  etc passwd    filename is ignored when piped in on standard input   cat  etc passwd   wc -l 41    unusual redirection  but wc still ignores the filename    lt   etc passwd wc -l 41    typical redirection  taking standard input from a file   wc -l  lt   etc passwd 41   As you can see  the only time wc will print the filename is when its passed as an argument  rather than as data on standard input  In some cases  you may want the filename to be printed  so it s useful to understand when it will be displayed

User · Answer

apply on Mac  and probably other Unixes   Actually there is a problem with the wc approach  it does not count the last line if it does not terminate with the end of line symbol   Use this instead  nbLines   cat -n file txt   tail -n 1   cut -f1   xargs    or even better  thanks gniourf gniourf    nblines   grep -c    file txt    Note  The awk approach by chilicuil also works

User · Answer

It s a very simple   NUMOFLINES   cat  JAVA TAGS FILE   wc -l     or  NUMOFLINES   wc -l  JAVA TAGS FILE   awk   print  1

User · Answer

You can also use awk   awk  END  print NR  lines    filename  Or   awk  END  print NR   filename

User · Answer

I normally use the  back tick  feature of bash  export NUM LINES  wc -l filename    Note the  tick  is the  back tick  e g    not the normal single quote

[bash] bash echo number of lines of file given in a bash variable without the file name

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