Unix commands(a-e)

man --is Online UNIX manual: man-pages:It gives detailed instructions on all of the commands listed here and a lot more.See man man for more... cat filename1 > filename2 :This overwrite contents of filename2 with filename1 cat filename1 » filename2 :This appends contents of filename1 to filename2. cd /usr: Changes current directory to /usr directory cd .. : Change current directory to previous higher directory. cd : Change to home of current userid. chgrp group1 filename1 : Change group id to group 1 for filename1. chgrp -R group1 * : Changes group id of all files in current and subdirectories to group 1. chmod ugo+rwx filename1: Add read/write/execute permission to filename1 for user/owner, group and others (world). chmod o x filename1 : Remove execute from others (world) chmod 751 filename1 : Set rwx for user/owner, group and others; r=4, w=2, x=1, rwx=7 rx=5, rw=6, wx=3, none=0. chown sam filename1 : Change owner of file filename1 to sam. chown -R sam * : Change owner to sam for all files in current and subdirectories. clear :Clear the terminal screen. compress filename1 : Compress file filename1 and replace it with filename1.Z cp filename1 filename2 : Copy file filename1 to filename2 destroying the contents of filename2. cp -i * /usr/local/bin : Copy all files in current directory to /usr/local/bin directory; Prompt before overwriting files (i) cpio : Copy file archives to disk/tape crontab -e : Edit crontab file for current user crontab -e bill : Edit crontab file for user bill crontab -l : List crontab entries for current userid csh : Start the c shell process cut -d: -f1,5 /etc/passwd : Extract the 1st and 5th fields (username & real name) from file /etc/passwd where delimiter is colon who | cut -d" " -f1: List login names from who command date : Display current date string date +%D : Display current date, MM/DD/YY format dd : Copy file(s) to/from raw devices df : Displays free disk blocks and modes on file systems. df -k : Displays free space in kilobytes for mounted file systems echo name : Displays literal "name" on screen echo $PATH : Displays PATH environment variable ed/edit/ex : Alternative line editors, see vi env Displays current environment variables or allows setting