there are many ways to view the contents of a file
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commands[]
- 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 files[]
- 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
pipes[]
- 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