【Linux入門】head コマンド：ファイルの先頭を表示する

$ head /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin

$ head -n 20 /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin

（省略）

colord:x:997:994:User for colord:/var/lib/colord:/sbin/nologin
rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin
saned:x:996:993:SANE scanner daemon user:/usr/share/sane:/sbin/nologin

$ head -c 100 /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nol

$ head -q /etc/*.conf
# Please see http://dev.maxmind.com/geoip/geoipupdate/ for instructions
# on setting up geoipupdate, including information on how to download a
# pre-filled GeoIP.conf file.

# Enter your account ID and license key below. These are available from
# https://www.maxmind.com/en/my_license_key. If you are only using free
# GeoLite databases, you may leave the 0 values.
AccountID 0
（省略）

$ ps aux | head -5
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.3 193968  7032 ?        Ss   21:15   0:01 /usr/lib/systemd/systemd --switched-root --system --deserialize 22
root         2  0.0  0.0      0     0 ?        S    21:15   0:00 [kthreadd]
root         4  0.0  0.0      0     0 ?        S<   21:15   0:00 [kworker/0:0H]
root         5  0.0  0.0      0     0 ?        S    21:15   0:00 [kworker/u2:0]

$ head -20 /etc/passwd | tail
games:x:12:100:games:/usr/games:/sbin/nologin
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
systemd-network:x:192:192:systemd Network Management:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
polkitd:x:999:998:User for polkitd:/:/sbin/nologin
libstoragemgmt:x:998:995:daemon account for libstoragemgmt:/var/run/lsm:/sbin/nologin
colord:x:997:994:User for colord:/var/lib/colord:/sbin/nologin
rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin
saned:x:996:993:SANE scanner daemon user:/usr/share/sane:/sbin/nologin