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How to display the contents of a file in unix

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there are many ways to view the contents of a file

Difficulty easy
About:Ratings


commandsEdit

  • cat command: print all the contents of the file in terminal. If the contents of your file is larger than a page, cat will not stop paging through the program until it hits the end
Hint: shift-page up and shift-page down allow you to page up and down in you terminal, so you can view previous output
  • more: prints the contents of a file. If the file is more than a page, it waits and allows you to scroll down the page with the down arrow key. It does not let you go up in the file
  • less: is like more but allows you to go up and down in the file. It also uses page up and page down, and many other functions like searching.

See: Howto use the less command

Commands for displaying parts of filesEdit

  • head: displays the first 10(default) lines of a file
-c, --bytes=[-]N
print the first N bytes of each file; with the leading `-',print all but the last N bytes of each file
-n, --lines=[-]N
print the first N lines instead of the first 10; with the leading `-', print all but the last N lines of each file
-q, --quiet, --silent
never print headers giving file names
-v, --verbose
always print headers giving file names
  • tail: similar to head except prints the last 10(default) lines of a file.
--retry
keep trying to open a file even if it is inaccessible when tail starts or if it becomes inaccessible later -- useful only with -f
-c, --bytes=N
output the last N bytes
-f, --follow[={name|descriptor}] output appended data as the file grows;
-f, --follow, and --follow=descriptor are equivalent
-n, --lines=N
output the last N lines, instead of the last 10
--max-unchanged-stats=N
with --follow=name, reopen a FILE which has not changed size after N (default 5) iterations to see if it has been unlinked or renamed (this is the usual case of rotated log files)
--pid=PID
with -f, terminate after process ID, PID dies
-q, --quiet, --silent
never output headers giving file names
-s, --sleep-interval=S
with -f, each iteration lasts approximately S (default 1) seconds
-v, --verbose
always output headers giving file names
--help display this help and exit
--version
output version information and exit
  • grep: displays all lines that match a specified phrase
Usage: grep phrase filename
See: Howto use the grep command
  • sed : sed is very complex.
See: Howto use the sed command


  • gawk : gawk is very complex.
See: Howto use the gawk command

pipesEdit

  • cat filename|head
same as head filename
  • cat filename|tail
same as head filename
  • cat filename|more
same as more filename
  • cat filename|grep phrase
same as head phrase filename
  • cat filename|head|grep phrase
prints the first 10 line that have if they have phrase in them
same as head filename|grep phrase
  • cat filename|grep phrase|head
prints the first 10 line that have phrase in them
same as grep phrase filename|head

See AlsoEdit

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